diff --git a/build_config/MinGW.gfortran.default/build_rules.mk b/build_config/MinGW.gfortran.default/build_rules.mk
index 3d06a67b5d..24f9fbfbbe 100644
--- a/build_config/MinGW.gfortran.default/build_rules.mk
+++ b/build_config/MinGW.gfortran.default/build_rules.mk
@@ -10,6 +10,20 @@ ESMF_F90DEFAULT         = gfortran
 ESMF_CXXDEFAULT         = g++
 ESMF_CDEFAULT           = gcc
 
+############################################################
+# Use the GNU dialect (gnu++/gnu) instead of strict ISO (c++/c). On MinGW the
+# strict -std=c++NN / -std=cNN flags define __STRICT_ANSI__, which makes the CRT
+# headers (<io.h>, <unistd.h>) hide their POSIX-named entry points (dup, dup2,
+# close, open, read, write, ...). ESMF's VM code uses those names, so the strict
+# dialect breaks the build. The GNU dialect keeps them visible.
+#
+ifneq ($(ESMF_CXXSTD),sysdefault)
+ESMF_CXXSTDFLAG         = -std=gnu++$(ESMF_CXXSTD)
+endif
+ifneq ($(ESMF_CSTD),sysdefault)
+ESMF_CSTDFLAG           = -std=gnu$(ESMF_CSTD)
+endif
+
 ############################################################
 # Default MPI setting.
 #
@@ -96,7 +110,20 @@ endif
 ifeq ($(ESMF_ABI),64)
 ESMF_ABISTRING := x86_64_small
 endif
-else
+endif
+# 64-bit MSYS2/MinGW reports `uname -m` as x86_64; accept it alongside the legacy
+# i686 label (mirrors the Linux.gfortran ABISTRING handling). ESMF_ABI still selects
+# the 32- vs 64-bit memory model.
+ifeq ($(ESMF_MACHINE),x86_64)
+ESMF_ABISTRING := x86_64_small
+ifeq ($(ESMF_ABI),32)
+ESMF_ABISTRING := x86_64_32
+endif
+ifeq ($(ESMF_ABI),64)
+ESMF_ABISTRING := x86_64_small
+endif
+endif
+ifeq ($(ESMF_ABISTRING),)
 $(error "ESMF_MACHINE = $(ESMF_MACHINE)" not recognized)
 endif
 
@@ -149,8 +176,10 @@ ESMF_CXXCOMPILECPPFLAGS += -DESMF_NO_SYSTEMCALL
 
 ############################################################
 # Windows does not have support for the times system call
+# (also define it for C: vendored Zoltan timer.c is C and includes sys/times.h)
 #
 ESMF_CXXCOMPILECPPFLAGS += -DNO_TIMES
+ESMF_CCOMPILECPPFLAGS   += -DNO_TIMES
 
 ############################################################
 # Windows does not have support for Pthreads
@@ -212,7 +241,14 @@ ESMF_CXXLINKLIBS += -lgfortran -lWs2_32
 ############################################################
 # Shared library options
 #
-ESMF_SL_LIBOPTS  += -shared
+# --export-all-symbols is required: parts of the tree (yaml-cpp, MOAB/mesquite,
+# MOAB Factory.cpp, verdict, ESMCI_Trace, nlohmann/json) decorate symbols with
+# __declspec(dllexport). As soon as ANY symbol is explicitly exported, MinGW ld
+# stops auto-exporting the rest, so the undecorated extern "C" ESMC_* / ESMF C API
+# (e.g. ESMC_Initialize) is absent from the DLL export table and ctypes can't find
+# it. Forcing all globals to be exported restores the Unix-.so-like behavior ESMPy
+# expects.
+ESMF_SL_LIBOPTS  += -shared -Wl,--export-all-symbols
 ESMF_SL_LIBLIBS       += $(ESMF_CXXLINKPATHS) $(ESMF_CXXLINKLIBS) -lgfortran
 
 ############################################################
diff --git a/src/Infrastructure/Base/interface/ESMF_Info.F90 b/src/Infrastructure/Base/interface/ESMF_Info.F90
index 250ca4a7ba..fa6b190af6 100644
--- a/src/Infrastructure/Base/interface/ESMF_Info.F90
+++ b/src/Infrastructure/Base/interface/ESMF_Info.F90
@@ -893,7 +893,7 @@ subroutine ESMF_InfoGetI8(info, key, value, keywordEnforcer, default, idx, attne
   integer, intent(out), optional :: rc
 
   integer :: localrc
-  integer(C_LONG), target :: local_default
+  integer(ESMF_KIND_I8), target :: local_default
   integer(C_INT), target :: local_idx
   type(C_PTR) :: local_default_ptr, local_idx_ptr
   integer(C_INT) :: recursive, strlen_only
diff --git a/src/Infrastructure/Base/interface/ESMF_InfoCDef.F90 b/src/Infrastructure/Base/interface/ESMF_InfoCDef.F90
index c09c884595..6d2c236f22 100644
--- a/src/Infrastructure/Base/interface/ESMF_InfoCDef.F90
+++ b/src/Infrastructure/Base/interface/ESMF_InfoCDef.F90
@@ -3,7 +3,7 @@
   function c_info_base_get(base_address) bind(C, name="ESMC_BaseGetInfo")
     use iso_c_binding
     implicit none
-    integer(C_LONG), intent(in) :: base_address
+    integer(C_LONG_LONG), intent(in) :: base_address
     type(C_PTR) :: c_info_base_get
   end function c_info_base_get
 
@@ -66,8 +66,8 @@ subroutine c_info_copyforattribute(isrc, idst, rc) bind(C, name="ESMC_InfoCopyFo
   subroutine c_info_copyforattribute_reference(src_base_address, dst_base_address, rc) bind(C, name="ESMC_InfoCopyForAttributeReference")
     use iso_c_binding
     implicit none
-    integer(C_LONG) :: src_base_address
-    integer(C_LONG) :: dst_base_address
+    integer(C_LONG_LONG) :: src_base_address
+    integer(C_LONG_LONG) :: dst_base_address
     integer(C_INT), intent(out) :: rc
   end subroutine
   
@@ -205,7 +205,7 @@ subroutine c_info_base_sync(inqstate, rootPet, vmAddress, markClean, rc) bind(C,
     implicit none
     type(C_PTR), value :: inqstate
     integer(C_INT), intent(in) :: rootPet
-    integer(C_LONG), intent(in) :: vmAddress
+    integer(C_LONG_LONG), intent(in) :: vmAddress
     integer(C_INT), intent(in) :: markClean
     integer(C_INT), intent(out) :: rc
   end subroutine
diff --git a/src/Infrastructure/Mesh/src/Moab/DiscreteGeometry/makefile b/src/Infrastructure/Mesh/src/Moab/DiscreteGeometry/makefile
index 6b6ce974ed..a63d5ca543 100644
--- a/src/Infrastructure/Mesh/src/Moab/DiscreteGeometry/makefile
+++ b/src/Infrastructure/Mesh/src/Moab/DiscreteGeometry/makefile
@@ -3,7 +3,13 @@
 # leave alone.
 ALL: build_here 
 
-ESMF_CXXCOMPILECPPFLAGS += -DIS_BUILDING_MB -DHAVE_VSNPRINTF -DLINUX -DUSE_MPI
+ESMF_CXXCOMPILECPPFLAGS += -DIS_BUILDING_MB -DHAVE_VSNPRINTF -DUSE_MPI
+# -DLINUX selects MOAB's Unix code paths (dlfcn.h, dirent.h in Core.cpp).
+# Those headers do not exist on MinGW; leave LINUX undefined there so MOAB
+# uses its POSIX/Windows-safe fallbacks. Kept for Linux and Darwin.
+ifneq ($(ESMF_OS),MinGW)
+ESMF_CXXCOMPILECPPFLAGS += -DLINUX
+endif
 
 SOURCEC = \
   DGMSolver.cpp HiReconstruction.cpp
diff --git a/src/Infrastructure/Mesh/src/Moab/IntxMesh/makefile b/src/Infrastructure/Mesh/src/Moab/IntxMesh/makefile
index 45627ee930..fcd148aa7a 100644
--- a/src/Infrastructure/Mesh/src/Moab/IntxMesh/makefile
+++ b/src/Infrastructure/Mesh/src/Moab/IntxMesh/makefile
@@ -3,7 +3,13 @@
 # leave alone.
 ALL: build_here 
 
-ESMF_CXXCOMPILECPPFLAGS += -DIS_BUILDING_MB -DHAVE_VSNPRINTF -DLINUX -DUSE_MPI
+ESMF_CXXCOMPILECPPFLAGS += -DIS_BUILDING_MB -DHAVE_VSNPRINTF -DUSE_MPI
+# -DLINUX selects MOAB's Unix code paths (dlfcn.h, dirent.h in Core.cpp).
+# Those headers do not exist on MinGW; leave LINUX undefined there so MOAB
+# uses its POSIX/Windows-safe fallbacks. Kept for Linux and Darwin.
+ifneq ($(ESMF_OS),MinGW)
+ESMF_CXXCOMPILECPPFLAGS += -DLINUX
+endif
 
 SOURCEC = \
   Intx2Mesh.cpp Intx2MeshInPlane.cpp Intx2MeshOnSphere.cpp \
diff --git a/src/Infrastructure/Mesh/src/Moab/LocalDiscretization/makefile b/src/Infrastructure/Mesh/src/Moab/LocalDiscretization/makefile
index 5d7cebcb4d..33001eb459 100644
--- a/src/Infrastructure/Mesh/src/Moab/LocalDiscretization/makefile
+++ b/src/Infrastructure/Mesh/src/Moab/LocalDiscretization/makefile
@@ -3,7 +3,13 @@
 # leave alone.
 ALL: build_here 
 
-ESMF_CXXCOMPILECPPFLAGS += -DIS_BUILDING_MB -DHAVE_VSNPRINTF -DLINUX -DUSE_MPI
+ESMF_CXXCOMPILECPPFLAGS += -DIS_BUILDING_MB -DHAVE_VSNPRINTF -DUSE_MPI
+# -DLINUX selects MOAB's Unix code paths (dlfcn.h, dirent.h in Core.cpp).
+# Those headers do not exist on MinGW; leave LINUX undefined there so MOAB
+# uses its POSIX/Windows-safe fallbacks. Kept for Linux and Darwin.
+ifneq ($(ESMF_OS),MinGW)
+ESMF_CXXCOMPILECPPFLAGS += -DLINUX
+endif
 
 SOURCEC = ElemEvaluator.cpp LinearHex.cpp LinearQuad.cpp \
   LinearTet.cpp LinearTri.cpp QuadraticHex.cpp 
diff --git a/src/Infrastructure/Mesh/src/Moab/io/makefile b/src/Infrastructure/Mesh/src/Moab/io/makefile
index 962a96b1cb..8117dcd381 100644
--- a/src/Infrastructure/Mesh/src/Moab/io/makefile
+++ b/src/Infrastructure/Mesh/src/Moab/io/makefile
@@ -3,7 +3,13 @@
 # leave alone.
 ALL: build_here 
 
-ESMF_CXXCOMPILECPPFLAGS += -DIS_BUILDING_MB -DHAVE_VSNPRINTF -DLINUX -DUSE_MPI
+ESMF_CXXCOMPILECPPFLAGS += -DIS_BUILDING_MB -DHAVE_VSNPRINTF -DUSE_MPI
+# -DLINUX selects MOAB's Unix code paths (dlfcn.h, dirent.h in Core.cpp).
+# Those headers do not exist on MinGW; leave LINUX undefined there so MOAB
+# uses its POSIX/Windows-safe fallbacks. Kept for Linux and Darwin.
+ifneq ($(ESMF_OS),MinGW)
+ESMF_CXXCOMPILECPPFLAGS += -DLINUX
+endif
 
 SOURCEC = \
 	ExoIIUtil.cpp FileTokenizer.cpp GmshUtil.cpp \
diff --git a/src/Infrastructure/Mesh/src/Moab/makefile b/src/Infrastructure/Mesh/src/Moab/makefile
index 8a746698b9..ced29651cf 100644
--- a/src/Infrastructure/Mesh/src/Moab/makefile
+++ b/src/Infrastructure/Mesh/src/Moab/makefile
@@ -3,7 +3,13 @@
 # leave alone.
 ALL: build_here 
 
-ESMF_CXXCOMPILECPPFLAGS += -DIS_BUILDING_MB -DHAVE_VSNPRINTF -DLINUX -DUSE_MPI
+ESMF_CXXCOMPILECPPFLAGS += -DIS_BUILDING_MB -DHAVE_VSNPRINTF -DUSE_MPI
+# -DLINUX selects MOAB's Unix code paths (dlfcn.h, dirent.h in Core.cpp).
+# Those headers do not exist on MinGW; leave LINUX undefined there so MOAB
+# uses its POSIX/Windows-safe fallbacks. Kept for Linux and Darwin.
+ifneq ($(ESMF_OS),MinGW)
+ESMF_CXXCOMPILECPPFLAGS += -DLINUX
+endif
 
 SOURCEC = \
   AdaptiveKDTree.cpp AEntityFactory.cpp AffineXform.cpp AxisBox.cpp \
diff --git a/src/Infrastructure/Mesh/src/Moab/moab/Matrix3.hpp b/src/Infrastructure/Mesh/src/Moab/moab/Matrix3.hpp
index d620aa3dbd..e8071a4019 100644
--- a/src/Infrastructure/Mesh/src/Moab/moab/Matrix3.hpp
+++ b/src/Infrastructure/Mesh/src/Moab/moab/Matrix3.hpp
@@ -71,7 +71,18 @@
 
 // We will rely on LAPACK directly
 
-#ifdef WIN32
+// RLO: Only use ESMF-internal LAPACK subroutines with ESMF internal LAPACK.
+//      It seems like only dgeev and dsyevd are currently in use with MOAB.
+//      ESMF-internal LAPACK does not currently support dsyevr, dgetrf, dgetri.
+//      NOTE: this must be checked before the WIN32 case below. MinGW predefines
+//      WIN32, but the ESMF-internal LAPACK still exposes only the esmf_-prefixed
+//      names, so they must be used on Windows too -- otherwise the link fails
+//      with undefined references to dgeev_/dsyevd_.
+#if defined ESMF_LAPACK_INTERNAL
+#define MOAB_dgeev  MOAB_FC_WRAPPER(esmf_dgeev, ESMF_DGEEV)
+#define MOAB_dsyevd MOAB_FC_WRAPPER(esmf_dsyevd, ESMF_DSYEVD)
+
+#elif defined( WIN32 )
 
 // Should use second form below for windows but
 // needed to do this to make it work.
@@ -82,31 +93,11 @@
 #define MOAB_dgetrf MOAB_FC_FUNC( dgetrf, DGETRF )
 #define MOAB_dgetri MOAB_FC_FUNC( dgetri, DGETRI )
 
-#else
-
-// RLO: Only use ESMF-internal LAPACK subroutines with ESMF internal LAPACK.
-//      It seems like only dgeev and dsyevd are currently in use with MOAB.
-//      ESMF-internal LAPACK does not currently support dsyevr, dgetrf, dgetri.
-#if defined ESMF_LAPACK_INTERNAL
-#define MOAB_dgeev  MOAB_FC_WRAPPER(esmf_dgeev, ESMF_DGEEV)
-#define MOAB_dsyevd MOAB_FC_WRAPPER(esmf_dsyevd, ESMF_DSYEVD)
 #elif defined ESMF_LAPACK
 #define MOAB_dgeev  MOAB_FC_WRAPPER(dgeev, DGEEV)
 #define MOAB_dsyevd MOAB_FC_WRAPPER(dsyevd, DSYEVD)
 #endif
 
-// #define MOAB_dsyevr MOAB_FC_FUNC(dsyevr, DSYEVR)
-// #define MOAB_dgetrf MOAB_FC_FUNC(dgetrf, DGETRF)
-// #define MOAB_dgetri MOAB_FC_FUNC(dgetri, DGETRI)
-
-// #define MOAB_dsyevd MOAB_FC_WRAPPER( dsyevd, DSYEVD )
-// #define MOAB_dsyevr MOAB_FC_WRAPPER( dsyevr, DSYEVR )
-// #define MOAB_dgeev  MOAB_FC_WRAPPER( dgeev, DGEEV )
-// #define MOAB_dgetrf MOAB_FC_WRAPPER( dgetrf, DGETRF )
-// #define MOAB_dgetri MOAB_FC_WRAPPER( dgetri, DGETRI )
-
-#endif
-
 extern "C" {
 
 // Computes all eigenvalues and, optionally, eigenvectors of a
diff --git a/src/Infrastructure/Mesh/src/Moab/parallel/makefile b/src/Infrastructure/Mesh/src/Moab/parallel/makefile
index f81e93a319..275c3e7a3e 100644
--- a/src/Infrastructure/Mesh/src/Moab/parallel/makefile
+++ b/src/Infrastructure/Mesh/src/Moab/parallel/makefile
@@ -3,7 +3,13 @@
 # leave alone.
 ALL: build_here 
 
-ESMF_CXXCOMPILECPPFLAGS += -DIS_BUILDING_MB -DHAVE_VSNPRINTF -DLINUX -DUSE_MPI
+ESMF_CXXCOMPILECPPFLAGS += -DIS_BUILDING_MB -DHAVE_VSNPRINTF -DUSE_MPI
+# -DLINUX selects MOAB's Unix code paths (dlfcn.h, dirent.h in Core.cpp).
+# Those headers do not exist on MinGW; leave LINUX undefined there so MOAB
+# uses its POSIX/Windows-safe fallbacks. Kept for Linux and Darwin.
+ifneq ($(ESMF_OS),MinGW)
+ESMF_CXXCOMPILECPPFLAGS += -DLINUX
+endif
 
 SOURCEC = \
   gs.cpp ParallelComm.cpp ParallelData.cpp ParallelMergeMesh.cpp \
diff --git a/src/Infrastructure/Mesh/src/Moab/verdict/makefile b/src/Infrastructure/Mesh/src/Moab/verdict/makefile
index 59c600dda1..cb7f7c1ea1 100644
--- a/src/Infrastructure/Mesh/src/Moab/verdict/makefile
+++ b/src/Infrastructure/Mesh/src/Moab/verdict/makefile
@@ -3,7 +3,13 @@
 # leave alone.
 ALL: build_here 
 
-ESMF_CXXCOMPILECPPFLAGS += -DIS_BUILDING_MB -DHAVE_VSNPRINTF -DLINUX -DUSE_MPI
+ESMF_CXXCOMPILECPPFLAGS += -DIS_BUILDING_MB -DHAVE_VSNPRINTF -DUSE_MPI
+# -DLINUX selects MOAB's Unix code paths (dlfcn.h, dirent.h in Core.cpp).
+# Those headers do not exist on MinGW; leave LINUX undefined there so MOAB
+# uses its POSIX/Windows-safe fallbacks. Kept for Linux and Darwin.
+ifneq ($(ESMF_OS),MinGW)
+ESMF_CXXCOMPILECPPFLAGS += -DLINUX
+endif
 
 SOURCEC = V_EdgeMetric.cpp VerdictVector.cpp VerdictWrapper.cpp \
   V_GaussIntegration.cpp V_HexMetric.cpp V_KnifeMetric.cpp \
diff --git a/src/Infrastructure/Util/include/dmp_diff.hpp b/src/Infrastructure/Util/include/dmp_diff.hpp
index 7d98ce6cf0..82da502acb 100644
--- a/src/Infrastructure/Util/include/dmp_diff.hpp
+++ b/src/Infrastructure/Util/include/dmp_diff.hpp
@@ -31,15 +31,20 @@
 
 using namespace std;
 
-enum Operation : int8_t { EQUAL=0, INSERT=1, DELETE=2 };
+// Enumerators are prefixed with OP_ to avoid collisions with preprocessor
+// macros from system headers -- notably <windows.h>, which #defines DELETE
+// (a Win32 access-right constant) on MinGW/Windows. A plain `DELETE` here would
+// be macro-expanded before compilation, so the prefix is required for the
+// MinGW build; renaming all three keeps the set consistent.
+enum Operation : int8_t { OP_EQUAL=0, OP_INSERT=1, OP_DELETE=2 };
 
 inline char op2chr(Operation op) {
     switch (op) {
-        case DELETE:
+        case OP_DELETE:
             return '-';
-        case INSERT:
+        case OP_INSERT:
             return '+';
-        case EQUAL:
+        case OP_EQUAL:
             return '=';
         default:
             return '?';
@@ -187,7 +192,7 @@ class MyersDiff {
         Diffs diffs{};
         if (text1 == text2) {
             if (text1.size() != 0) {
-                diffs.push_back(Diff(EQUAL, text1));
+                diffs.push_back(Diff(OP_EQUAL, text1));
             }
             return diffs;
         }
@@ -209,10 +214,10 @@ class MyersDiff {
 
         // Restore the prefix and suffix.
         if (commonprefix.size() != 0) {
-            diffs.insert(diffs.begin(), Diff(EQUAL, commonprefix));
+            diffs.insert(diffs.begin(), Diff(OP_EQUAL, commonprefix));
         }
         if (commonsuffix.size() != 0) {
-            diffs.push_back(Diff(EQUAL, commonsuffix));
+            diffs.push_back(Diff(OP_EQUAL, commonsuffix));
         }
 
         // TODO diff_cleanupMerge(diffs);
@@ -235,13 +240,13 @@ class MyersDiff {
 
         if (text1.size() == 0) {
             // Just add some text (speedup).
-            diffs.push_back(Diff(INSERT, text2));
+            diffs.push_back(Diff(OP_INSERT, text2));
             return diffs;
         }
 
         if (text2.size() == 0) {
             // Just delete some text (speedup).
-            diffs.push_back(Diff(DELETE, text1));
+            diffs.push_back(Diff(OP_DELETE, text1));
             return diffs;
         }
 
@@ -250,9 +255,9 @@ class MyersDiff {
         int i = longtext.find(shorttext);
         if (i != -1) {
             // Shorter text is inside the longer text (speedup).
-            Operation op = (text1.size() > text2.size()) ? DELETE : INSERT;
+            Operation op = (text1.size() > text2.size()) ? OP_DELETE : OP_INSERT;
             diffs.push_back(Diff(op, longtext.substr(0, i)));
-            diffs.push_back(Diff(EQUAL, shorttext));
+            diffs.push_back(Diff(OP_EQUAL, shorttext));
             diffs.push_back(Diff(op, longtext.substr(i + shorttext.size())));
             return diffs;
         }
@@ -260,8 +265,8 @@ class MyersDiff {
         if (shorttext.size() == 1) {
             // Single character string.
             // After the previous speedup, the character can't be an equality.
-            diffs.push_back(Diff(DELETE, text1));
-            diffs.push_back(Diff(INSERT, text2));
+            diffs.push_back(Diff(OP_DELETE, text1));
+            diffs.push_back(Diff(OP_INSERT, text2));
             return diffs;
         }
 
@@ -281,7 +286,7 @@ class MyersDiff {
                                                checklines, deadline);
           // Merge the results.
           diffs = diffs_a;
-          diffs.push_back(Diff(EQUAL, mid_common));
+          diffs.push_back(Diff(OP_EQUAL, mid_common));
           diffs.addAll(diffs_b);
           return diffs;
         }
@@ -417,8 +422,8 @@ class MyersDiff {
         // Diff took too long and hit the deadline or
         // number of diffs equals number of characters, no commonality at all.
         Diffs diffs{};
-        diffs.push_back(Diff{DELETE, text1});
-        diffs.push_back(Diff{INSERT, text2});
+        diffs.push_back(Diff{OP_DELETE, text1});
+        diffs.push_back(Diff{OP_INSERT, text2});
         return diffs;
     }
 
@@ -642,7 +647,7 @@ class MyersDiff {
       int length_deletions2 = 0;
       Diff thisDiff = pointer.next();
       while (thisDiff != null) {
-        if (thisDiff.operation == EQUAL) {
+        if (thisDiff.operation == OP_EQUAL) {
           // Equality found.
           equalities.push(thisDiff);
           length_insertions1 = length_insertions2;
@@ -652,7 +657,7 @@ class MyersDiff {
           lastEquality = thisDiff.text;
         } else {
           // An insertion or deletion.
-          if (thisDiff.operation == INSERT) {
+          if (thisDiff.operation == OP_INSERT) {
             length_insertions2 += thisDiff.text.size();
           } else {
             length_deletions2 += thisDiff.text.size();
@@ -671,9 +676,9 @@ class MyersDiff {
             pointer.next();
 
             // Replace equality with a delete.
-            pointer.set(Diff(DELETE, lastEquality));
+            pointer.set(Diff(OP_DELETE, lastEquality));
             // Insert a corresponding an insert.
-            pointer.push_back(Diff(INSERT, lastEquality));
+            pointer.push_back(Diff(OP_INSERT, lastEquality));
 
             equalities.pop();  // Throw away the equality we just deleted.
             if (!equalities.isEmpty()) {
@@ -726,8 +731,8 @@ class MyersDiff {
         }
       }
       while (thisDiff != null) {
-        if (prevDiff.operation == DELETE &&
-            thisDiff.operation == INSERT) {
+        if (prevDiff.operation == OP_DELETE &&
+            thisDiff.operation == OP_INSERT) {
           String deletion = prevDiff.text;
           String insertion = thisDiff.text;
           int overlap_length1 = diff_commonOverlap(deletion, insertion);
@@ -736,7 +741,7 @@ class MyersDiff {
             if (overlap_length1 >= deletion.size() / 2.0 ||
                 overlap_length1 >= insertion.size() / 2.0) {
               // Overlap found. Insert an equality and trim the surrounding
-    edits. pointer.previous(); pointer.push_back(Diff(EQUAL,
+    edits. pointer.previous(); pointer.push_back(Diff(OP_EQUAL,
                                    insertion.substring(0, overlap_length1)));
               prevDiff.text =
                   deletion.substring(0, deletion.size() - overlap_length1);
@@ -750,12 +755,12 @@ class MyersDiff {
               // Reverse overlap found.
               // Insert an equality and swap and trim the surrounding edits.
               pointer.previous();
-              pointer.push_back(Diff(EQUAL,
+              pointer.push_back(Diff(OP_EQUAL,
                                    deletion.substring(0, overlap_length2)));
-              prevDiff.operation = INSERT;
+              prevDiff.operation = OP_INSERT;
               prevDiff.text =
                 insertion.substring(0, insertion.size() - overlap_length2);
-              thisDiff.operation = DELETE;
+              thisDiff.operation = OP_DELETE;
               thisDiff.text = deletion.substring(overlap_length2);
               // pointer.add inserts the element before the cursor, so there is
               // no need to step past the new element.
@@ -788,8 +793,8 @@ class MyersDiff {
       Diff nextDiff = pointer.hasNext() ? pointer.next() : null;
       // Intentionally ignore the first and last element (don't need checking).
       while (nextDiff != null) {
-        if (prevDiff.operation == EQUAL &&
-            nextDiff.operation == EQUAL) {
+        if (prevDiff.operation == OP_EQUAL &&
+            nextDiff.operation == OP_EQUAL) {
           // This is a single edit surrounded by equalities.
           equality1 = prevDiff.text;
           edit = thisDiff.text;
@@ -933,7 +938,7 @@ class MyersDiff {
       bool post_del = false;
       Diff thisDiff = pointer.next();
       Diff safeDiff = thisDiff;  // The last Diff that is known to be
-    unsplittable. while (thisDiff != null) { if (thisDiff.operation == EQUAL) {
+    unsplittable. while (thisDiff != null) { if (thisDiff.operation == OP_EQUAL) {
           // Equality found.
           if (thisDiff.text.size() < Diff_EditCost && (post_ins || post_del))
     {
@@ -951,7 +956,7 @@ class MyersDiff {
           post_ins = post_del = false;
         } else {
           // An insertion or deletion.
-          if (thisDiff.operation == DELETE) {
+          if (thisDiff.operation == OP_DELETE) {
             post_del = true;
           } else {
             post_ins = true;
@@ -977,9 +982,9 @@ class MyersDiff {
             pointer.next();
 
             // Replace equality with a delete.
-            pointer.set(Diff(DELETE, lastEquality));
+            pointer.set(Diff(OP_DELETE, lastEquality));
             // Insert a corresponding an insert.
-            pointer.push_back(thisDiff = Diff(INSERT, lastEquality));
+            pointer.push_back(thisDiff = Diff(OP_INSERT, lastEquality));
 
             equalities.pop();  // Throw away the equality we just deleted.
             lastEquality = null;
@@ -1025,7 +1030,7 @@ class MyersDiff {
      * @param diffs std::vector of Diff objects.
      *
     void diff_cleanupMerge(Diffs diffs) {
-      diffs.push_back(Diff(EQUAL, ""));  // Add a dummy entry at the end.
+      diffs.push_back(Diff(OP_EQUAL, ""));  // Add a dummy entry at the end.
       std::vectorIterator<Diff> pointer = diffs.listIterator();
       int count_delete = 0;
       int count_insert = 0;
@@ -1036,17 +1041,17 @@ class MyersDiff {
       int commonlength;
       while (thisDiff != null) {
         switch (thisDiff.operation) {
-        case INSERT:
+        case OP_INSERT:
           count_insert++;
           text_insert += thisDiff.text;
           prevEqual = null;
           break;
-        case DELETE:
+        case OP_DELETE:
           count_delete++;
           text_delete += thisDiff.text;
           prevEqual = null;
           break;
-        case EQUAL:
+        case OP_EQUAL:
           if (count_delete + count_insert > 1) {
             bool both_types = count_delete != 0 && count_insert != 0;
             // Delete the offending records.
@@ -1065,12 +1070,12 @@ class MyersDiff {
               if (commonlength != 0) {
                 if (pointer.hasPrevious()) {
                   thisDiff = pointer.previous();
-                  assert thisDiff.operation == EQUAL
+                  assert thisDiff.operation == OP_EQUAL
                          : "Previous diff should have been an equality.";
                   thisDiff.text += text_insert.substring(0, commonlength);
                   pointer.next();
                 } else {
-                  pointer.push_back(Diff(EQUAL,
+                  pointer.push_back(Diff(OP_EQUAL,
                       text_insert.substring(0, commonlength)));
                 }
                 text_insert = text_insert.substring(commonlength);
@@ -1091,10 +1096,10 @@ class MyersDiff {
             }
             // Insert the merged records.
             if (text_delete.size() != 0) {
-              pointer.push_back(Diff(DELETE, text_delete));
+              pointer.push_back(Diff(OP_DELETE, text_delete));
             }
             if (text_insert.size() != 0) {
-              pointer.push_back(Diff(INSERT, text_insert));
+              pointer.push_back(Diff(OP_INSERT, text_insert));
             }
             // Step forward to the equality.
             thisDiff = pointer.hasNext() ? pointer.next() : null;
@@ -1133,8 +1138,8 @@ class MyersDiff {
       Diff nextDiff = pointer.hasNext() ? pointer.next() : null;
       // Intentionally ignore the first and last element (don't need checking).
       while (nextDiff != null) {
-        if (prevDiff.operation == EQUAL &&
-            nextDiff.operation == EQUAL) {
+        if (prevDiff.operation == OP_EQUAL &&
+            nextDiff.operation == OP_EQUAL) {
           // This is a single edit surrounded by equalities.
           if (thisDiff.text.endsWith(prevDiff.text)) {
             // Shift the edit over the previous equality.
@@ -1179,7 +1184,7 @@ class MyersDiff {
     String diff_text1(Diffs diffs) {
         Range text{};
         for (Diff aDiff : diffs) {
-            if (aDiff.operation != INSERT) {
+            if (aDiff.operation != OP_INSERT) {
                 text.append(aDiff.text);
             }
         }
@@ -1194,7 +1199,7 @@ class MyersDiff {
     String diff_text2(Diffs diffs) {
         Range text{};
         for (Diff aDiff : diffs) {
-            if (aDiff.operation != DELETE) {
+            if (aDiff.operation != OP_DELETE) {
                 text.append(aDiff.text);
             }
         }
@@ -1210,9 +1215,9 @@ class MyersDiff {
         Stats ret;
         for (const auto &i : result) {
             switch (i.operation) {
-                case EQUAL:  ret.equal += i.text.size(); break;
-                case INSERT: ret.inserted += i.text.size(); break;
-                case DELETE: ret.deleted += i.text.size(); break;
+                case OP_EQUAL:  ret.equal += i.text.size(); break;
+                case OP_INSERT: ret.inserted += i.text.size(); break;
+                case OP_DELETE: ret.deleted += i.text.size(); break;
             }
         }
         return ret;
diff --git a/src/Infrastructure/VM/include/ESMCI_VMKernel.h b/src/Infrastructure/VM/include/ESMCI_VMKernel.h
index cde27db536..9881ae2cce 100644
--- a/src/Infrastructure/VM/include/ESMCI_VMKernel.h
+++ b/src/Infrastructure/VM/include/ESMCI_VMKernel.h
@@ -40,6 +40,21 @@
 #include <sys/time.h>
 #else
 #include <windows.h>
+// <windows.h> (via the COM headers) defines `interface` as a macro (== struct),
+// which collides with identifiers named `interface` in headers included later --
+// notably MOAB's moab/Interface.hpp. ESMF/MOAB do not use COM, so drop it.
+#undef interface
+#include <io.h>       // Windows CRT: dup, dup2, close, open (used by Redirects)
+// Windows has no unistd.h STD*_FILENO constants; define the POSIX values.
+#ifndef STDIN_FILENO
+#define STDIN_FILENO  0
+#endif
+#ifndef STDOUT_FILENO
+#define STDOUT_FILENO 1
+#endif
+#ifndef STDERR_FILENO
+#define STDERR_FILENO 2
+#endif
 #endif
 
 #ifndef ESMF_NO_OPENMP
diff --git a/src/Infrastructure/VM/src/ESMCI_VMKernel.C b/src/Infrastructure/VM/src/ESMCI_VMKernel.C
index 030e968128..c6b32f48a9 100644
--- a/src/Infrastructure/VM/src/ESMCI_VMKernel.C
+++ b/src/Infrastructure/VM/src/ESMCI_VMKernel.C
@@ -1015,7 +1015,7 @@ VMK::Redirects VMK::setRedirects(void *ssarg){
   Redirects reds;
   // stdout and stderr redirect
   if (sarg->stdoutName.length()){
-    reds.oldStdout = fcntl(STDOUT_FILENO, F_DUPFD, 0);  // keep access to stdout
+    reds.oldStdout = dup(STDOUT_FILENO);  // keep access to stdout (== fcntl F_DUPFD,0)
     if (reds.oldStdout == -1){
       int localrc;
       ESMC_LogDefault.MsgFoundError(ESMC_RC_INTNRL_BAD,
@@ -1036,7 +1036,7 @@ VMK::Redirects VMK::setRedirects(void *ssarg){
     reds.oldStdout = -1;  // indicate no redirect
   }
   if (sarg->stderrName.length()){
-    reds.oldStderr = fcntl(STDERR_FILENO, F_DUPFD, 0);  // keep access to stderr
+    reds.oldStderr = dup(STDERR_FILENO);  // keep access to stderr (== fcntl F_DUPFD,0)
     if (reds.oldStderr == -1){
       int localrc;
       ESMC_LogDefault.MsgFoundError(ESMC_RC_INTNRL_BAD,
diff --git a/src/Infrastructure/stubs/mpiuni/mpi.h b/src/Infrastructure/stubs/mpiuni/mpi.h
index ed74256466..07822c5943 100644
--- a/src/Infrastructure/stubs/mpiuni/mpi.h
+++ b/src/Infrastructure/stubs/mpiuni/mpi.h
@@ -59,6 +59,11 @@
 #if !defined(__MPI_H)
 #define __MPI_H
 
+/* intptr_t: a pointer-sized integer for the argument-swallowing casts below.
+   On Win64 (LLP64) `long` is 32-bit while pointers are 64-bit, so casting a
+   pointer through `(long)` truncates it; intptr_t is pointer-sized everywhere. */
+#include <stdint.h>
+
 #ifdef __cplusplus
 extern "C" {
 #endif
@@ -246,240 +251,240 @@ extern double ESMC_MPI_Wtime(void);
 */
 
 #define MPI_Init(argc,argv) \
-     (MPIUNI_TMP = (void*)(long) (argc),\
-      MPIUNI_TMP = (void*)(long) (argv),\
+     (MPIUNI_TMP = (void*)(intptr_t) (argc),\
+      MPIUNI_TMP = (void*)(intptr_t) (argv),\
       MPI_SUCCESS)
 #define MPI_Init_thread(argc,argv,required,provided) \
-     (MPIUNI_TMP = (void*)(long) (argc),\
-      MPIUNI_TMP = (void*)(long) (argv),\
-      MPIUNI_TMP = (void*)(long) (required),\
-      MPIUNI_TMP = (void*)(long) (provided),\
+     (MPIUNI_TMP = (void*)(intptr_t) (argc),\
+      MPIUNI_TMP = (void*)(intptr_t) (argv),\
+      MPIUNI_TMP = (void*)(intptr_t) (required),\
+      MPIUNI_TMP = (void*)(intptr_t) (provided),\
       MPI_SUCCESS)
 #define MPI_Send(buf,count,datatype,dest,tag,comm)  \
-     (MPIUNI_TMP = (void*)(long) (buf),\
-      MPIUNI_TMP = (void*)(long) (count),\
-      MPIUNI_TMP = (void*)(long) (datatype),\
-      MPIUNI_TMP = (void*)(long) (dest),\
-      MPIUNI_TMP = (void*)(long) (tag),\
-      MPIUNI_TMP = (void*)(long) (comm),\
+     (MPIUNI_TMP = (void*)(intptr_t) (buf),\
+      MPIUNI_TMP = (void*)(intptr_t) (count),\
+      MPIUNI_TMP = (void*)(intptr_t) (datatype),\
+      MPIUNI_TMP = (void*)(intptr_t) (dest),\
+      MPIUNI_TMP = (void*)(intptr_t) (tag),\
+      MPIUNI_TMP = (void*)(intptr_t) (comm),\
       MPI_SUCCESS)
 #define MPI_Recv(buf,count,datatype,source,tag,comm,status) \
-     (MPIUNI_TMP = (void*)(long) (buf),\
-      MPIUNI_TMP = (void*)(long) (count),\
-      MPIUNI_TMP = (void*)(long) (datatype),\
-      MPIUNI_TMP = (void*)(long) (source),\
-      MPIUNI_TMP = (void*)(long) (tag),\
-      MPIUNI_TMP = (void*)(long) (comm),\
-      MPIUNI_TMP = (void*)(long) (status),\
+     (MPIUNI_TMP = (void*)(intptr_t) (buf),\
+      MPIUNI_TMP = (void*)(intptr_t) (count),\
+      MPIUNI_TMP = (void*)(intptr_t) (datatype),\
+      MPIUNI_TMP = (void*)(intptr_t) (source),\
+      MPIUNI_TMP = (void*)(intptr_t) (tag),\
+      MPIUNI_TMP = (void*)(intptr_t) (comm),\
+      MPIUNI_TMP = (void*)(intptr_t) (status),\
       MPI_Abort(MPI_COMM_WORLD,0))
 #define MPI_Get_count(status, datatype,count) \
-     (MPIUNI_TMP = (void*)(long) (status),\
-      MPIUNI_TMP = (void*)(long) (datatype),\
-      MPIUNI_TMP = (void*)(long) (count),\
+     (MPIUNI_TMP = (void*)(intptr_t) (status),\
+      MPIUNI_TMP = (void*)(intptr_t) (datatype),\
+      MPIUNI_TMP = (void*)(intptr_t) (count),\
       MPI_Abort(MPI_COMM_WORLD,0))
 #define MPI_Bsend(buf,count,datatype,dest,tag,comm)  \
-     (MPIUNI_TMP = (void*)(long) (buf),\
-      MPIUNI_TMP = (void*)(long) (count),\
-      MPIUNI_TMP = (void*)(long) (datatype),\
-      MPIUNI_TMP = (void*)(long) (dest),\
-      MPIUNI_TMP = (void*)(long) (tag),\
-      MPIUNI_TMP = (void*)(long) (comm),\
+     (MPIUNI_TMP = (void*)(intptr_t) (buf),\
+      MPIUNI_TMP = (void*)(intptr_t) (count),\
+      MPIUNI_TMP = (void*)(intptr_t) (datatype),\
+      MPIUNI_TMP = (void*)(intptr_t) (dest),\
+      MPIUNI_TMP = (void*)(intptr_t) (tag),\
+      MPIUNI_TMP = (void*)(intptr_t) (comm),\
       MPI_SUCCESS)
 #define MPI_Ssend(buf,count, datatype,dest,tag,comm) \
-     (MPIUNI_TMP = (void*)(long) (buf),\
-      MPIUNI_TMP = (void*)(long) (count),\
-      MPIUNI_TMP = (void*)(long) (datatype),\
-      MPIUNI_TMP = (void*)(long) (dest),\
-      MPIUNI_TMP = (void*)(long) (tag),\
-      MPIUNI_TMP = (void*)(long) (comm),\
+     (MPIUNI_TMP = (void*)(intptr_t) (buf),\
+      MPIUNI_TMP = (void*)(intptr_t) (count),\
+      MPIUNI_TMP = (void*)(intptr_t) (datatype),\
+      MPIUNI_TMP = (void*)(intptr_t) (dest),\
+      MPIUNI_TMP = (void*)(intptr_t) (tag),\
+      MPIUNI_TMP = (void*)(intptr_t) (comm),\
       MPI_SUCCESS)
 #define MPI_Rsend(buf,count, datatype,dest,tag,comm) \
-     (MPIUNI_TMP = (void*)(long) (buf),\
-      MPIUNI_TMP = (void*)(long) (count),\
-      MPIUNI_TMP = (void*)(long) (datatype),\
-      MPIUNI_TMP = (void*)(long) (dest),\
-      MPIUNI_TMP = (void*)(long) (tag),\
-      MPIUNI_TMP = (void*)(long) (comm),\
+     (MPIUNI_TMP = (void*)(intptr_t) (buf),\
+      MPIUNI_TMP = (void*)(intptr_t) (count),\
+      MPIUNI_TMP = (void*)(intptr_t) (datatype),\
+      MPIUNI_TMP = (void*)(intptr_t) (dest),\
+      MPIUNI_TMP = (void*)(intptr_t) (tag),\
+      MPIUNI_TMP = (void*)(intptr_t) (comm),\
       MPI_SUCCESS)
 #define MPI_Buffer_attach(buffer,size) \
-     (MPIUNI_TMP = (void*)(long) (buffer),\
-      MPIUNI_TMP = (void*)(long) (size),\
+     (MPIUNI_TMP = (void*)(intptr_t) (buffer),\
+      MPIUNI_TMP = (void*)(intptr_t) (size),\
       MPI_SUCCESS)
 #define MPI_Buffer_detach(buffer,size)\
-     (MPIUNI_TMP = (void*)(long) (buffer),\
-      MPIUNI_TMP = (void*)(long) (size),\
+     (MPIUNI_TMP = (void*)(intptr_t) (buffer),\
+      MPIUNI_TMP = (void*)(intptr_t) (size),\
       MPI_SUCCESS)
 #define MPI_Ibsend(buf,count, datatype,dest,tag,comm,request) \
-     (MPIUNI_TMP = (void*)(long) (buf),\
-       MPIUNI_TMP = (void*)(long) (count),\
-       MPIUNI_TMP = (void*)(long) (datatype),\
-       MPIUNI_TMP = (void*)(long) (dest),\
-       MPIUNI_TMP = (void*)(long) (tag),\
-       MPIUNI_TMP = (void*)(long) (comm),\
-       MPIUNI_TMP = (void*)(long) (request),\
+     (MPIUNI_TMP = (void*)(intptr_t) (buf),\
+       MPIUNI_TMP = (void*)(intptr_t) (count),\
+       MPIUNI_TMP = (void*)(intptr_t) (datatype),\
+       MPIUNI_TMP = (void*)(intptr_t) (dest),\
+       MPIUNI_TMP = (void*)(intptr_t) (tag),\
+       MPIUNI_TMP = (void*)(intptr_t) (comm),\
+       MPIUNI_TMP = (void*)(intptr_t) (request),\
        MPI_SUCCESS)
 #define MPI_Issend(buf,count, datatype,dest,tag,comm,request) \
-     (MPIUNI_TMP = (void*)(long) (buf),\
-      MPIUNI_TMP = (void*)(long) (count),\
-      MPIUNI_TMP = (void*)(long) (datatype),\
-      MPIUNI_TMP = (void*)(long) (dest),\
-      MPIUNI_TMP = (void*)(long) (tag),\
-      MPIUNI_TMP = (void*)(long) (comm),\
-      MPIUNI_TMP = (void*)(long) (request),\
+     (MPIUNI_TMP = (void*)(intptr_t) (buf),\
+      MPIUNI_TMP = (void*)(intptr_t) (count),\
+      MPIUNI_TMP = (void*)(intptr_t) (datatype),\
+      MPIUNI_TMP = (void*)(intptr_t) (dest),\
+      MPIUNI_TMP = (void*)(intptr_t) (tag),\
+      MPIUNI_TMP = (void*)(intptr_t) (comm),\
+      MPIUNI_TMP = (void*)(intptr_t) (request),\
       MPI_SUCCESS)
 #define MPI_Irsend(buf,count, datatype,dest,tag,comm,request) \
-     (MPIUNI_TMP = (void*)(long) (buf),\
-      MPIUNI_TMP = (void*)(long) (count),\
-      MPIUNI_TMP = (void*)(long) (datatype),\
-      MPIUNI_TMP = (void*)(long) (dest),\
-      MPIUNI_TMP = (void*)(long) (tag),\
-      MPIUNI_TMP = (void*)(long) (comm),\
-      MPIUNI_TMP = (void*)(long) (request),\
+     (MPIUNI_TMP = (void*)(intptr_t) (buf),\
+      MPIUNI_TMP = (void*)(intptr_t) (count),\
+      MPIUNI_TMP = (void*)(intptr_t) (datatype),\
+      MPIUNI_TMP = (void*)(intptr_t) (dest),\
+      MPIUNI_TMP = (void*)(intptr_t) (tag),\
+      MPIUNI_TMP = (void*)(intptr_t) (comm),\
+      MPIUNI_TMP = (void*)(intptr_t) (request),\
       MPI_SUCCESS)
 #define MPI_Irecv(buf,count, datatype,source,tag,comm,request) \
-     (MPIUNI_TMP = (void*)(long) (buf),\
-      MPIUNI_TMP = (void*)(long) (count),\
-      MPIUNI_TMP = (void*)(long) (datatype),\
-      MPIUNI_TMP = (void*)(long) (source),\
-      MPIUNI_TMP = (void*)(long) (tag),\
-      MPIUNI_TMP = (void*)(long) (comm),\
-      MPIUNI_TMP = (void*)(long) (request),\
+     (MPIUNI_TMP = (void*)(intptr_t) (buf),\
+      MPIUNI_TMP = (void*)(intptr_t) (count),\
+      MPIUNI_TMP = (void*)(intptr_t) (datatype),\
+      MPIUNI_TMP = (void*)(intptr_t) (source),\
+      MPIUNI_TMP = (void*)(intptr_t) (tag),\
+      MPIUNI_TMP = (void*)(intptr_t) (comm),\
+      MPIUNI_TMP = (void*)(intptr_t) (request),\
       MPI_Abort(MPI_COMM_WORLD,0))
 #define MPI_Isend(buf,count, datatype,dest,tag,comm,request) \
-     (MPIUNI_TMP = (void*)(long) (buf),\
-      MPIUNI_TMP = (void*)(long) (count),\
-      MPIUNI_TMP = (void*)(long) (datatype),\
-      MPIUNI_TMP = (void*)(long) (dest),\
-      MPIUNI_TMP = (void*)(long) (tag),\
-      MPIUNI_TMP = (void*)(long) (comm),\
-      MPIUNI_TMP = (void*)(long) (request),\
+     (MPIUNI_TMP = (void*)(intptr_t) (buf),\
+      MPIUNI_TMP = (void*)(intptr_t) (count),\
+      MPIUNI_TMP = (void*)(intptr_t) (datatype),\
+      MPIUNI_TMP = (void*)(intptr_t) (dest),\
+      MPIUNI_TMP = (void*)(intptr_t) (tag),\
+      MPIUNI_TMP = (void*)(intptr_t) (comm),\
+      MPIUNI_TMP = (void*)(intptr_t) (request),\
       MPI_Abort(MPI_COMM_WORLD,0))
 #define MPI_Wait(request,status) \
-     (MPIUNI_TMP = (void*)(long) (request),\
-      MPIUNI_TMP = (void*)(long) (status),\
+     (MPIUNI_TMP = (void*)(intptr_t) (request),\
+      MPIUNI_TMP = (void*)(intptr_t) (status),\
       MPI_SUCCESS)
 #define MPI_Test(request,flag,status) \
-     (MPIUNI_TMP = (void*)(long) (request),\
-      MPIUNI_TMP = (void*)(long) (status),\
+     (MPIUNI_TMP = (void*)(intptr_t) (request),\
+      MPIUNI_TMP = (void*)(intptr_t) (status),\
       *(flag) = 0, \
       MPI_SUCCESS)
 #define MPI_Request_free(request) \
-     (MPIUNI_TMP = (void*)(long) (request),\
+     (MPIUNI_TMP = (void*)(intptr_t) (request),\
       MPI_SUCCESS)
 #define MPI_Waitany(a,b,c,d) \
-     (MPIUNI_TMP = (void*)(long) (a),\
-      MPIUNI_TMP = (void*)(long) (b),\
-      MPIUNI_TMP = (void*)(long) (c),\
-      MPIUNI_TMP = (void*)(long) (d),\
+     (MPIUNI_TMP = (void*)(intptr_t) (a),\
+      MPIUNI_TMP = (void*)(intptr_t) (b),\
+      MPIUNI_TMP = (void*)(intptr_t) (c),\
+      MPIUNI_TMP = (void*)(intptr_t) (d),\
       MPI_SUCCESS)
 #define MPI_Testany(a,b,c,d,e) \
-     (MPIUNI_TMP = (void*)(long) (a),\
-      MPIUNI_TMP = (void*)(long) (b),\
-      MPIUNI_TMP = (void*)(long) (c),\
-      MPIUNI_TMP = (void*)(long) (d),\
-      MPIUNI_TMP = (void*)(long) (e),\
+     (MPIUNI_TMP = (void*)(intptr_t) (a),\
+      MPIUNI_TMP = (void*)(intptr_t) (b),\
+      MPIUNI_TMP = (void*)(intptr_t) (c),\
+      MPIUNI_TMP = (void*)(intptr_t) (d),\
+      MPIUNI_TMP = (void*)(intptr_t) (e),\
       MPI_SUCCESS)
 #define MPI_Waitall(count,array_of_requests,array_of_statuses) \
-     (MPIUNI_TMP = (void*)(long) (count),\
-      MPIUNI_TMP = (void*)(long) (array_of_requests),\
-      MPIUNI_TMP = (void*)(long) (array_of_statuses),\
+     (MPIUNI_TMP = (void*)(intptr_t) (count),\
+      MPIUNI_TMP = (void*)(intptr_t) (array_of_requests),\
+      MPIUNI_TMP = (void*)(intptr_t) (array_of_statuses),\
       MPI_SUCCESS)
 #define MPI_Testall(count,array_of_requests,flag,array_of_statuses) \
-     (MPIUNI_TMP = (void*)(long) (count),\
-      MPIUNI_TMP = (void*)(long) (array_of_requests),\
-      MPIUNI_TMP = (void*)(long) (flag),\
-      MPIUNI_TMP = (void*)(long) (array_of_statuses),\
+     (MPIUNI_TMP = (void*)(intptr_t) (count),\
+      MPIUNI_TMP = (void*)(intptr_t) (array_of_requests),\
+      MPIUNI_TMP = (void*)(intptr_t) (flag),\
+      MPIUNI_TMP = (void*)(intptr_t) (array_of_statuses),\
       MPI_SUCCESS)
 #define MPI_Waitsome(incount,array_of_requests,outcount,\
                      array_of_indices,array_of_statuses) \
-     (MPIUNI_TMP = (void*)(long) (incount),\
-      MPIUNI_TMP = (void*)(long) (array_of_requests),\
-      MPIUNI_TMP = (void*)(long) (outcount),\
-      MPIUNI_TMP = (void*)(long) (array_of_indices),\
-      MPIUNI_TMP = (void*)(long) (array_of_statuses),\
+     (MPIUNI_TMP = (void*)(intptr_t) (incount),\
+      MPIUNI_TMP = (void*)(intptr_t) (array_of_requests),\
+      MPIUNI_TMP = (void*)(intptr_t) (outcount),\
+      MPIUNI_TMP = (void*)(intptr_t) (array_of_indices),\
+      MPIUNI_TMP = (void*)(intptr_t) (array_of_statuses),\
       MPI_SUCCESS)
 #define MPI_Comm_group(comm,group) \
-     (MPIUNI_TMP = (void*)(long) (comm),\
-      MPIUNI_TMP = (void*)(long) (group),\
+     (MPIUNI_TMP = (void*)(intptr_t) (comm),\
+      MPIUNI_TMP = (void*)(intptr_t) (group),\
       MPI_SUCCESS)
 #define MPI_Group_incl(group,n,ranks,newgroup) \
-     (MPIUNI_TMP = (void*)(long) (group),\
-      MPIUNI_TMP = (void*)(long) (n),\
-      MPIUNI_TMP = (void*)(long) (ranks),\
-      MPIUNI_TMP = (void*)(long) (newgroup),\
+     (MPIUNI_TMP = (void*)(intptr_t) (group),\
+      MPIUNI_TMP = (void*)(intptr_t) (n),\
+      MPIUNI_TMP = (void*)(intptr_t) (ranks),\
+      MPIUNI_TMP = (void*)(intptr_t) (newgroup),\
       MPI_SUCCESS)
 #define MPI_Testsome(incount,array_of_requests,outcount,\
                      array_of_indices,array_of_statuses) MPI_SUCCESS
 #define MPI_Iprobe(source,tag,comm,flag,status) (*(flag)=0, MPI_SUCCESS)
 #define MPI_Probe(source,tag,comm,status) MPI_SUCCESS
-#define MPI_Cancel(request) (MPIUNI_TMP = (void*)(long) (request),MPI_SUCCESS)
+#define MPI_Cancel(request) (MPIUNI_TMP = (void*)(intptr_t) (request),MPI_SUCCESS)
 #define MPI_Test_cancelled(status,flag) (*(flag)=0,MPI_SUCCESS)
 #define MPI_Send_init(buf,count, datatype,dest,tag,comm,request) \
-     (MPIUNI_TMP = (void*)(long) (buf),\
-     MPIUNI_TMP = (void*)(long) (count),\
-     MPIUNI_TMP = (void*)(long) (datatype),\
-     MPIUNI_TMP = (void*)(long) (dest),\
-     MPIUNI_TMP = (void*)(long) (tag),\
-     MPIUNI_TMP = (void*)(long) (comm),\
-     MPIUNI_TMP = (void*)(long) (request),\
+     (MPIUNI_TMP = (void*)(intptr_t) (buf),\
+     MPIUNI_TMP = (void*)(intptr_t) (count),\
+     MPIUNI_TMP = (void*)(intptr_t) (datatype),\
+     MPIUNI_TMP = (void*)(intptr_t) (dest),\
+     MPIUNI_TMP = (void*)(intptr_t) (tag),\
+     MPIUNI_TMP = (void*)(intptr_t) (comm),\
+     MPIUNI_TMP = (void*)(intptr_t) (request),\
      MPI_SUCCESS)
 #define MPI_Bsend_init(buf,count, datatype,dest,tag,comm,request) \
-     (MPIUNI_TMP = (void*)(long) (buf),\
-     MPIUNI_TMP = (void*)(long) (count),\
-     MPIUNI_TMP = (void*)(long) (datatype),\
-     MPIUNI_TMP = (void*)(long) (dest),\
-     MPIUNI_TMP = (void*)(long) (tag),\
-     MPIUNI_TMP = (void*)(long) (comm),\
-     MPIUNI_TMP = (void*)(long) (request),\
+     (MPIUNI_TMP = (void*)(intptr_t) (buf),\
+     MPIUNI_TMP = (void*)(intptr_t) (count),\
+     MPIUNI_TMP = (void*)(intptr_t) (datatype),\
+     MPIUNI_TMP = (void*)(intptr_t) (dest),\
+     MPIUNI_TMP = (void*)(intptr_t) (tag),\
+     MPIUNI_TMP = (void*)(intptr_t) (comm),\
+     MPIUNI_TMP = (void*)(intptr_t) (request),\
      MPI_SUCCESS)
 #define MPI_Ssend_init(buf,count, datatype,dest,tag,comm,request) \
-     (MPIUNI_TMP = (void*)(long) (buf),\
-     MPIUNI_TMP = (void*)(long) (count),\
-     MPIUNI_TMP = (void*)(long) (datatype),\
-     MPIUNI_TMP = (void*)(long) (dest),\
-     MPIUNI_TMP = (void*)(long) (tag),\
-     MPIUNI_TMP = (void*)(long) (comm),\
-     MPIUNI_TMP = (void*)(long) (request),\
+     (MPIUNI_TMP = (void*)(intptr_t) (buf),\
+     MPIUNI_TMP = (void*)(intptr_t) (count),\
+     MPIUNI_TMP = (void*)(intptr_t) (datatype),\
+     MPIUNI_TMP = (void*)(intptr_t) (dest),\
+     MPIUNI_TMP = (void*)(intptr_t) (tag),\
+     MPIUNI_TMP = (void*)(intptr_t) (comm),\
+     MPIUNI_TMP = (void*)(intptr_t) (request),\
      MPI_SUCCESS)
 #define MPI_Bsend_init(buf,count, datatype,dest,tag,comm,request) \
-     (MPIUNI_TMP = (void*)(long) (buf),\
-     MPIUNI_TMP = (void*)(long) (count),\
-     MPIUNI_TMP = (void*)(long) (datatype),\
-     MPIUNI_TMP = (void*)(long) (dest),\
-     MPIUNI_TMP = (void*)(long) (tag),\
-     MPIUNI_TMP = (void*)(long) (comm),\
-     MPIUNI_TMP = (void*)(long) (request),\
+     (MPIUNI_TMP = (void*)(intptr_t) (buf),\
+     MPIUNI_TMP = (void*)(intptr_t) (count),\
+     MPIUNI_TMP = (void*)(intptr_t) (datatype),\
+     MPIUNI_TMP = (void*)(intptr_t) (dest),\
+     MPIUNI_TMP = (void*)(intptr_t) (tag),\
+     MPIUNI_TMP = (void*)(intptr_t) (comm),\
+     MPIUNI_TMP = (void*)(intptr_t) (request),\
      MPI_SUCCESS)
 #define MPI_Rsend_init(buf,count, datatype,dest,tag,comm,request) \
-     (MPIUNI_TMP = (void*)(long) (buf),\
-     MPIUNI_TMP = (void*)(long) (count),\
-     MPIUNI_TMP = (void*)(long) (datatype),\
-     MPIUNI_TMP = (void*)(long) (dest),\
-     MPIUNI_TMP = (void*)(long) (tag),\
-     MPIUNI_TMP = (void*)(long) (comm),\
-     MPIUNI_TMP = (void*)(long) (request),\
+     (MPIUNI_TMP = (void*)(intptr_t) (buf),\
+     MPIUNI_TMP = (void*)(intptr_t) (count),\
+     MPIUNI_TMP = (void*)(intptr_t) (datatype),\
+     MPIUNI_TMP = (void*)(intptr_t) (dest),\
+     MPIUNI_TMP = (void*)(intptr_t) (tag),\
+     MPIUNI_TMP = (void*)(intptr_t) (comm),\
+     MPIUNI_TMP = (void*)(intptr_t) (request),\
      MPI_SUCCESS)
 #define MPI_Recv_init(buf,count, datatype,source,tag,comm,request) \
-     (MPIUNI_TMP = (void*)(long) (buf),\
-     MPIUNI_TMP = (void*)(long) (count),\
-     MPIUNI_TMP = (void*)(long) (datatype),\
-     MPIUNI_TMP = (void*)(long) (source),\
-     MPIUNI_TMP = (void*)(long) (tag),\
-     MPIUNI_TMP = (void*)(long) (comm),\
-     MPIUNI_TMP = (void*)(long) (request),\
+     (MPIUNI_TMP = (void*)(intptr_t) (buf),\
+     MPIUNI_TMP = (void*)(intptr_t) (count),\
+     MPIUNI_TMP = (void*)(intptr_t) (datatype),\
+     MPIUNI_TMP = (void*)(intptr_t) (source),\
+     MPIUNI_TMP = (void*)(intptr_t) (tag),\
+     MPIUNI_TMP = (void*)(intptr_t) (comm),\
+     MPIUNI_TMP = (void*)(intptr_t) (request),\
      MPI_SUCCESS)
-#define MPI_Start(request) (MPIUNI_TMP = (void*)(long) (request),MPI_SUCCESS)
+#define MPI_Start(request) (MPIUNI_TMP = (void*)(intptr_t) (request),MPI_SUCCESS)
 #define MPI_Startall(count,array_of_requests) \
-     (MPIUNI_TMP = (void*)(long) (count),\
-     MPIUNI_TMP = (void*)(long) (array_of_requests),\
+     (MPIUNI_TMP = (void*)(intptr_t) (count),\
+     MPIUNI_TMP = (void*)(intptr_t) (array_of_requests),\
      MPI_SUCCESS)
 #define MPI_Op_create(function,commute,op) \
-     (MPIUNI_TMP = (void*)(long) (function),\
-     MPIUNI_TMP = (void*)(long) (commute),\
-     MPIUNI_TMP = (void*)(long) (op),\
+     (MPIUNI_TMP = (void*)(intptr_t) (function),\
+     MPIUNI_TMP = (void*)(intptr_t) (commute),\
+     MPIUNI_TMP = (void*)(intptr_t) (op),\
      MPI_SUCCESS)
 #define MPI_Op_free(op) \
-     (MPIUNI_TMP = (void*)(long) (op),\
+     (MPIUNI_TMP = (void*)(intptr_t) (op),\
      MPI_SUCCESS)
      /* Need to determine sizeof "sendtype" */
 #define MPI_Sendrecv(sendbuf,sendcount, sendtype,\
@@ -509,7 +514,7 @@ extern double ESMC_MPI_Wtime(void);
      MPI_Abort(MPI_COMM_WORLD,0)
 #define MPI_Type_ub(datatype,displacement) \
      MPI_Abort(MPI_COMM_WORLD,0)
-#define MPI_Type_commit(datatype) (MPIUNI_TMP = (void*)(long) (datatype),\
+#define MPI_Type_commit(datatype) (MPIUNI_TMP = (void*)(intptr_t) (datatype),\
      MPI_SUCCESS)
 #define MPI_Type_free(datatype) MPI_SUCCESS
 #define MPI_Get_elements(status, datatype,count) \
@@ -523,57 +528,57 @@ extern double ESMC_MPI_Wtime(void);
 #define MPI_Pack_size(incount, datatype,comm,size) \
      MPI_Abort(MPI_COMM_WORLD,0)
 #define MPI_Barrier(comm) \
-     (MPIUNI_TMP = (void*)(long) (comm),\
+     (MPIUNI_TMP = (void*)(intptr_t) (comm),\
      MPI_SUCCESS)
 #define MPI_Bcast(buffer,count,datatype,root,comm) \
-     (MPIUNI_TMP = (void*)(long) (buffer),\
-     MPIUNI_TMP = (void*)(long) (count),\
-     MPIUNI_TMP = (void*)(long) (datatype),\
-     MPIUNI_TMP = (void*)(long) (comm),\
+     (MPIUNI_TMP = (void*)(intptr_t) (buffer),\
+     MPIUNI_TMP = (void*)(intptr_t) (count),\
+     MPIUNI_TMP = (void*)(intptr_t) (datatype),\
+     MPIUNI_TMP = (void*)(intptr_t) (comm),\
      MPI_SUCCESS)
 #define MPI_Gather(sendbuf,sendcount, sendtype,\
      recvbuf,recvcount, recvtype,\
      root,comm) \
-     (MPIUNI_TMP = (void*)(long) (recvcount),\
-     MPIUNI_TMP = (void*)(long) (root),\
-     MPIUNI_TMP = (void*)(long) (recvtype),\
-     MPIUNI_TMP = (void*)(long) (comm),\
+     (MPIUNI_TMP = (void*)(intptr_t) (recvcount),\
+     MPIUNI_TMP = (void*)(intptr_t) (root),\
+     MPIUNI_TMP = (void*)(intptr_t) (recvtype),\
+     MPIUNI_TMP = (void*)(intptr_t) (comm),\
      MPIUNI_Memcpy(recvbuf,sendbuf,(sendcount)* (sendtype),CHECK_FOR_MPI_IN_PLACE_SOURCE),  \
      MPI_SUCCESS)
 #define MPI_Gatherv(sendbuf,sendcount, sendtype,\
      recvbuf,recvcounts,displs,\
      recvtype,root,comm) \
-     (MPIUNI_TMP = (void*)(long) (recvcounts),\
-     MPIUNI_TMP = (void*)(long) (displs),\
-     MPIUNI_TMP = (void*)(long) (recvtype),\
-     MPIUNI_TMP = (void*)(long) (root),\
-     MPIUNI_TMP = (void*)(long) (comm),\
+     (MPIUNI_TMP = (void*)(intptr_t) (recvcounts),\
+     MPIUNI_TMP = (void*)(intptr_t) (displs),\
+     MPIUNI_TMP = (void*)(intptr_t) (recvtype),\
+     MPIUNI_TMP = (void*)(intptr_t) (root),\
+     MPIUNI_TMP = (void*)(intptr_t) (comm),\
      MPIUNI_Memcpy(recvbuf,sendbuf,(sendcount)* (sendtype),CHECK_FOR_MPI_IN_PLACE_SOURCE),  \
      MPI_SUCCESS)
 #define MPI_Scatter(sendbuf,sendcount, sendtype,\
      recvbuf,recvcount, recvtype,\
      root,comm) \
-     (MPIUNI_TMP = (void*)(long) (sendbuf),\
-     MPIUNI_TMP = (void*)(long) (sendcount),\
-     MPIUNI_TMP = (void*)(long) (sendtype),\
-     MPIUNI_TMP = (void*)(long) (recvbuf),\
-     MPIUNI_TMP = (void*)(long) (recvcount),\
-     MPIUNI_TMP = (void*)(long) (recvtype),\
-     MPIUNI_TMP = (void*)(long) (root),\
-     MPIUNI_TMP = (void*)(long) (comm),MPI_Abort(MPI_COMM_WORLD,0))
+     (MPIUNI_TMP = (void*)(intptr_t) (sendbuf),\
+     MPIUNI_TMP = (void*)(intptr_t) (sendcount),\
+     MPIUNI_TMP = (void*)(intptr_t) (sendtype),\
+     MPIUNI_TMP = (void*)(intptr_t) (recvbuf),\
+     MPIUNI_TMP = (void*)(intptr_t) (recvcount),\
+     MPIUNI_TMP = (void*)(intptr_t) (recvtype),\
+     MPIUNI_TMP = (void*)(intptr_t) (root),\
+     MPIUNI_TMP = (void*)(intptr_t) (comm),MPI_Abort(MPI_COMM_WORLD,0))
 #define MPI_Allgather(sendbuf,sendcount, sendtype,\
      recvbuf,recvcount, recvtype,comm) \
-     (MPIUNI_TMP = (void*)(long) (recvcount),\
-     MPIUNI_TMP = (void*)(long) (recvtype),\
-     MPIUNI_TMP = (void*)(long) (comm),\
+     (MPIUNI_TMP = (void*)(intptr_t) (recvcount),\
+     MPIUNI_TMP = (void*)(intptr_t) (recvtype),\
+     MPIUNI_TMP = (void*)(intptr_t) (comm),\
      MPIUNI_Memcpy(recvbuf,sendbuf,(sendcount)* (sendtype),CHECK_FOR_MPI_IN_PLACE_SOURCE),  \
      MPI_SUCCESS)
 #define MPI_Allgatherv(sendbuf,sendcount, sendtype,\
      recvbuf,recvcounts,displs,recvtype,comm) \
-     (MPIUNI_TMP = (void*)(long) (recvcounts),\
-     MPIUNI_TMP = (void*)(long) (displs),\
-     MPIUNI_TMP = (void*)(long) (recvtype),\
-     MPIUNI_TMP = (void*)(long) (comm),\
+     (MPIUNI_TMP = (void*)(intptr_t) (recvcounts),\
+     MPIUNI_TMP = (void*)(intptr_t) (displs),\
+     MPIUNI_TMP = (void*)(intptr_t) (recvtype),\
+     MPIUNI_TMP = (void*)(intptr_t) (comm),\
      MPIUNI_Memcpy(recvbuf,sendbuf,(sendcount)* (sendtype),CHECK_FOR_MPI_IN_PLACE_SOURCE),  \
      MPI_SUCCESS)
 #define MPI_Alltoall(sendbuf,sendcount, sendtype,\
@@ -585,13 +590,13 @@ extern double ESMC_MPI_Wtime(void);
 #define MPI_Reduce(sendbuf, recvbuf,count,\
      datatype,op,root,comm) \
      (MPIUNI_Memcpy(recvbuf,sendbuf,(count)*(datatype),CHECK_FOR_MPI_IN_PLACE_SOURCE), \
-     MPIUNI_TMP = (void*)(long) (comm),MPI_SUCCESS)
+     MPIUNI_TMP = (void*)(intptr_t) (comm),MPI_SUCCESS)
 #define MPI_Allreduce(sendbuf, recvbuf,count,datatype,op,comm) \
      (MPIUNI_Memcpy(recvbuf,sendbuf,(count)*(datatype),CHECK_FOR_MPI_IN_PLACE_SOURCE), \
-     MPIUNI_TMP = (void*)(long) (comm),MPI_SUCCESS)
+     MPIUNI_TMP = (void*)(intptr_t) (comm),MPI_SUCCESS)
 #define MPI_Scan(sendbuf, recvbuf,count,datatype,op,comm) \
      (MPIUNI_Memcpy(recvbuf,sendbuf,(count)*(datatype),CHECK_FOR_MPI_IN_PLACE_SOURCE), \
-     MPIUNI_TMP = (void*)(long) (comm),MPI_SUCCESS)
+     MPIUNI_TMP = (void*)(intptr_t) (comm),MPI_SUCCESS)
 #define MPI_Reduce_scatter(sendbuf, recvbuf,recvcounts,\
      datatype,op,comm) \
      MPI_Abort(MPI_COMM_WORLD,0)
@@ -608,28 +613,28 @@ extern double ESMC_MPI_Wtime(void);
 #define MPI_Group_range_incl(group,n,ranges,newgroup) MPI_SUCCESS
 #define MPI_Group_range_excl(group,n,ranges,newgroup) MPI_SUCCESS
 #define MPI_Group_free(group) \
-     (MPIUNI_TMP = (void*)(long) (group),\
+     (MPIUNI_TMP = (void*)(intptr_t) (group),\
      MPI_SUCCESS)
 #define MPI_Comm_size(comm,size) \
-     (MPIUNI_TMP = (void*)(long) (comm),\
+     (MPIUNI_TMP = (void*)(intptr_t) (comm),\
      *(size)=1,\
      MPI_SUCCESS)
 #define MPI_Comm_rank(comm,rank) \
-     (MPIUNI_TMP = (void*)(long) (comm),\
+     (MPIUNI_TMP = (void*)(intptr_t) (comm),\
      *(rank)=0,\
      MPI_SUCCESS)
 #define MPI_Comm_compare(comm1,comm2,result) \
-     (MPIUNI_TMP = (void*)(long) (comm1),\
-     MPIUNI_TMP = (void*)(long) (comm2),\
+     (MPIUNI_TMP = (void*)(intptr_t) (comm1),\
+     MPIUNI_TMP = (void*)(intptr_t) (comm2),\
      *(result)=MPI_IDENT,\
      MPI_SUCCESS)
 #define MPI_Comm_create(comm,group,newcomm)  \
      (*(newcomm) =  (comm),\
-     MPIUNI_TMP = (void*)(long) (group),\
+     MPIUNI_TMP = (void*)(intptr_t) (group),\
      MPI_SUCCESS)
 #define MPI_Comm_create_group(comm,group,tag,newcomm)  \
      (*(newcomm) =  (comm),\
-     MPIUNI_TMP = (void*)(long) (group),\
+     MPIUNI_TMP = (void*)(intptr_t) (group),\
      MPI_SUCCESS)
 #define MPI_Comm_split(comm,color,key,newcomm) MPI_SUCCESS
 #define MPI_Comm_test_inter(comm,flag) (*(flag)=1,MPI_SUCCESS)
@@ -640,12 +645,12 @@ extern double ESMC_MPI_Wtime(void);
 #define MPI_Intercomm_merge(intercomm,high,newintracomm) MPI_SUCCESS
 
 #define MPI_Info_create(info) \
-  (MPIUNI_TMP = (void*)(long) (info),\
+  (MPIUNI_TMP = (void*)(intptr_t) (info),\
    MPI_SUCCESS)
 #define MPI_Info_set(info,key,value) \
-  (MPIUNI_TMP = (void*)(long) (info),\
-   MPIUNI_TMP = (void*)(long) (key),\
-   MPIUNI_TMP = (void*)(long) (value),\
+  (MPIUNI_TMP = (void*)(intptr_t) (info),\
+   MPIUNI_TMP = (void*)(intptr_t) (key),\
+   MPIUNI_TMP = (void*)(intptr_t) (value),\
    MPI_SUCCESS)
 
 #define MPI_Topo_test(comm,status) MPI_SUCCESS
@@ -673,16 +678,16 @@ extern double ESMC_MPI_Wtime(void);
 #define MPI_Get_processor_name(name,result_len) \
      (MPIUNI_Memcpy(name,"localhost",9*sizeof(char),CHECK_FOR_MPI_IN_PLACE_NONE),name[10] = 0,*(result_len) = 10)
 #define MPI_Errhandler_create(function,errhandler) \
-     (MPIUNI_TMP = (void*)(long) (errhandler),\
+     (MPIUNI_TMP = (void*)(intptr_t) (errhandler),\
      MPI_SUCCESS)
 #define MPI_Errhandler_set(comm,errhandler) \
-     (MPIUNI_TMP = (void*)(long) (comm),\
-     MPIUNI_TMP = (void*)(long) (errhandler),\
+     (MPIUNI_TMP = (void*)(intptr_t) (comm),\
+     MPIUNI_TMP = (void*)(intptr_t) (errhandler),\
      MPI_SUCCESS)
 #define MPI_Errhandler_get(comm,errhandler) MPI_SUCCESS
 #define MPI_Errhandler_free(errhandler) MPI_SUCCESS
 #define MPI_Error_string(errorcode,string,result_len) \
-  (MPIUNI_TMP = (void*)(long) (errorcode),\
+  (MPIUNI_TMP = (void*)(intptr_t) (errorcode),\
    string[0]='\0', \
    *result_len=0, \
    MPI_SUCCESS)
diff --git a/src/addon/esmpy/src/esmpy/__init__.py b/src/addon/esmpy/src/esmpy/__init__.py
index 3845eac743..72ffb40f13 100644
--- a/src/addon/esmpy/src/esmpy/__init__.py
+++ b/src/addon/esmpy/src/esmpy/__init__.py
@@ -89,8 +89,30 @@
 elif (sys.version_info >= (3,8)):
     # this requires Python 3.8 or higher
     import importlib.metadata as ilm
-    
-    msg = ilm.metadata("esmpy")
+
+    try:
+        msg = ilm.metadata("esmpy")
+    except ilm.PackageNotFoundError:
+        # ESMPy may be installed under a variant distribution name that ships the
+        # same `esmpy` import package -- e.g. `esmpy-mpich` (an MPI-enabled build
+        # whose wheel depends on the `mpich` runtime). The distribution name is
+        # not the import name, so resolve whichever distribution provides this
+        # package rather than assuming "esmpy".
+        _dist_name = None
+        _pkg_to_dists = getattr(ilm, "packages_distributions", lambda: {})()
+        _dists = _pkg_to_dists.get("esmpy")
+        if _dists:
+            _dist_name = _dists[0]
+        else:
+            # Fallback (Python 3.8/3.9 lack packages_distributions): scan installed
+            # distributions for the one shipping the top-level `esmpy` package.
+            for _d in ilm.distributions():
+                if "esmpy" in (_d.read_text("top_level.txt") or "").split():
+                    _dist_name = _d.metadata["Name"]
+                    break
+        if _dist_name is None:
+            raise
+        msg = ilm.metadata(_dist_name)
 
 # set the private metadata
 __name__ = msg["Name"]
diff --git a/src/addon/esmpy/src/esmpy/api/constants.py b/src/addon/esmpy/src/esmpy/api/constants.py
index 489fdf3682..842ce11009 100644
--- a/src/addon/esmpy/src/esmpy/api/constants.py
+++ b/src/addon/esmpy/src/esmpy/api/constants.py
@@ -36,7 +36,8 @@
 _ESMF_OS = None
 (_ESMF_OS_DARWIN,
  _ESMF_OS_LINUX,
- _ESMF_OS_UNICOS) = (-5,-4,-3)
+ _ESMF_OS_UNICOS,
+ _ESMF_OS_WINDOWS) = (-5,-4,-3,-2)
 
 # ESMF_NETCDF
 _ESMF_NETCDF = False
diff --git a/src/addon/esmpy/src/esmpy/interface/loadESMF.py b/src/addon/esmpy/src/esmpy/interface/loadESMF.py
index 25dac450f9..16663cd1e1 100644
--- a/src/addon/esmpy/src/esmpy/interface/loadESMF.py
+++ b/src/addon/esmpy/src/esmpy/interface/loadESMF.py
@@ -6,7 +6,8 @@
 import sys
 import traceback
 
-from esmpy.interface.loadESMF_helpers import _check_version
+from esmpy.interface.loadESMF_helpers import (_check_version, _find_esmf_mk,
+                                              _esmf_mk_is_bundled)
 import esmpy.api.constants as constants
 
 try:
@@ -20,21 +21,11 @@
 except:
     raise ImportError('The CTypes library cannot be found.')
 
-esmfmk = None
-try:
-    esmfmk = os.environ["ESMFMKFILE"]
-except KeyError:
-    # Try to guess with very common paths in normal installs (especially conda)
-    guesses = [
-        os.path.join(sys.prefix, 'lib', 'esmf.mk'),  # conda build of esmf
-        os.path.join(sys.prefix, 'Library', 'lib', 'esmf.mk')
-    ]
-    for path in guesses:
-        if os.path.isfile(path):
-            esmfmk = path
-            break
-    else:
-        raise ImportError('The esmf.mk file cannot be found. Pass its path in the ESMFMKFILE environment variable.')
+# The esmpy package directory (two levels up from this file: esmpy/interface/).
+# Used both to find an esmf.mk bundled inside a pip wheel and to detect that case.
+_PACKAGE_DIR = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
+
+esmfmk = _find_esmf_mk(os.environ, sys.prefix, _PACKAGE_DIR)
 
 #### INVESTIGATE esmf.mk ######################################################
 
@@ -92,6 +83,13 @@
 libsdir = libsdir.rstrip()
 esmfos = esmfos.rstrip()
 
+# For a pip wheel that bundles the ESMF library, the absolute ESMF_LIBSDIR baked
+# into esmf.mk at build time is invalid once the package is relocated into
+# site-packages. The bundled library sits next to esmf.mk, so resolve the library
+# directory relative to it. This is a no-op for conda/source/HPC installs.
+if _esmf_mk_is_bundled(esmfmk, _PACKAGE_DIR):
+    libsdir = os.path.dirname(os.path.abspath(esmfmk))
+
 # set _ESMF_OS
 if "Darwin" in esmfos:
     constants._ESMF_OS = constants._ESMF_OS_DARWIN
@@ -99,6 +97,10 @@
     constants._ESMF_OS = constants._ESMF_OS_LINUX
 elif "Unicos" in esmfos:
     constants._ESMF_OS = constants._ESMF_OS_UNICOS
+elif os.name == "nt":
+    # Windows (e.g. a MinGW build); the esmf.mk ESMF_OS string varies, so key off
+    # the running interpreter, which for a wheel always matches the target OS.
+    constants._ESMF_OS = constants._ESMF_OS_WINDOWS
 else:
     raise ValueError("Unrecognized ESMF_OS setting!")
 
@@ -128,12 +130,47 @@
 # point.
 constants._ESMF_USE_INMEM_FACTORS = use_inmem_factors
 
+#### MPI RUNTIME (real-MPI builds) ############################################
+
+# A real-MPI build (ESMF_COMM != mpiuni) links libesmf_fullylinked against the C
+# MPI runtime (libmpi). For a pip wheel we do NOT vendor libmpi: it is supplied by a
+# separate runtime wheel (e.g. `mpich` for the esmpy-mpich distribution, or
+# `openmpi` for esmpy-openmpi), which installs libmpi into <prefix>/lib via the
+# wheel "data" scheme -- a directory not on the default dynamic-loader search path.
+# Preload it here with RTLD_GLOBAL, before libesmf is dlopened, so libesmf's MPI
+# symbols bind to it. This stays comm-agnostic: try the known C libmpi sonames
+# (MPICH's libmpi.so.12, Open MPI's libmpi.so.40) and the unversioned fallback, and
+# load the first that is present. Best-effort: if none is there (a conda/HPC/system
+# MPI already on the loader path, or a serial build), skip and let the normal loader
+# search apply.
+if esmfcomm is not None and "mpiuni" not in esmfcomm:
+    import sysconfig
+    _mpi_libdir = os.path.join(sysconfig.get_paths()["data"], "lib")
+    if constants._ESMF_OS == constants._ESMF_OS_DARWIN:
+        _mpi_names = ("libmpi.12.dylib", "libmpi.40.dylib", "libmpi.dylib")
+    else:
+        _mpi_names = ("libmpi.so.12", "libmpi.so.40", "libmpi.so")
+    for _mpi_name in _mpi_names:
+        _mpi_path = os.path.join(_mpi_libdir, _mpi_name)
+        if os.path.exists(_mpi_path):
+            try:
+                ct.CDLL(_mpi_path, mode=ct.RTLD_GLOBAL)
+            except OSError:
+                pass
+            break
+
 #### SHARED LIBRARY ###########################################################
 
 # load the shared library for esmf
 try:
     if constants._ESMF_OS == constants._ESMF_OS_DARWIN:
         _ESMF = np.ctypeslib.load_library('libesmf_fullylinked',libsdir)
+    elif constants._ESMF_OS == constants._ESMF_OS_WINDOWS:
+        # Ensure the bundled dependency DLLs (also in libsdir) are on the search path.
+        if hasattr(os, "add_dll_directory"):
+            os.add_dll_directory(libsdir)
+        _ESMF = ct.CDLL(os.path.join(libsdir,'libesmf_fullylinked.dll'),
+                        mode=ct.RTLD_GLOBAL)
     else:
         _ESMF = ct.CDLL(os.path.join(libsdir,'libesmf_fullylinked.so'),
                         mode=ct.RTLD_GLOBAL)
diff --git a/src/addon/esmpy/src/esmpy/interface/loadESMF_helpers.py b/src/addon/esmpy/src/esmpy/interface/loadESMF_helpers.py
index 4f973c6fc6..32da8b040d 100644
--- a/src/addon/esmpy/src/esmpy/interface/loadESMF_helpers.py
+++ b/src/addon/esmpy/src/esmpy/interface/loadESMF_helpers.py
@@ -9,11 +9,55 @@
 loadESMF.py.
 """
 
+import os
 import re
 import warnings
 
 from esmpy.util.exceptions import VersionWarning, VersionMismatch
 
+def _find_esmf_mk(environ, sys_prefix, package_dir):
+    """
+    Locate the esmf.mk makefile fragment that describes the ESMF installation.
+
+    Resolution order:
+      1. The ESMFMKFILE environment variable, if set (returned as-is, matching the
+         historical behavior where a missing file surfaces later as an open() error).
+      2. A copy bundled inside the installed esmpy package (a pip wheel that ships
+         libesmf_fullylinked alongside esmf.mk); see _esmf_mk_is_bundled.
+      3. Common conda layouts under sys.prefix.
+
+    Raises ImportError if ESMFMKFILE is unset and no esmf.mk can be found.
+    """
+    if "ESMFMKFILE" in environ:
+        return environ["ESMFMKFILE"]
+
+    guesses = [
+        os.path.join(package_dir, "_esmf", "lib", "esmf.mk"),  # bundled in a wheel
+        os.path.join(sys_prefix, "lib", "esmf.mk"),            # conda build of esmf
+        os.path.join(sys_prefix, "Library", "lib", "esmf.mk"), # conda on Windows
+    ]
+    for path in guesses:
+        if os.path.isfile(path):
+            return path
+    raise ImportError("The esmf.mk file cannot be found. Pass its path in the "
+                      "ESMFMKFILE environment variable.")
+
+
+def _esmf_mk_is_bundled(esmf_mk, package_dir):
+    """
+    Return True if esmf_mk lives inside the installed esmpy package (i.e. a wheel
+    that bundles the ESMF library).
+
+    In that case the absolute ESMF_LIBSDIR baked into esmf.mk at build time is
+    meaningless once pip relocates the package, so the caller resolves the library
+    directory relative to esmf.mk instead. Returns False for conda/source/HPC
+    installs, where the baked path is authoritative and behavior is unchanged.
+    """
+    pkg = os.path.realpath(package_dir)
+    mk = os.path.realpath(esmf_mk)
+    return mk == pkg or mk.startswith(pkg + os.sep)
+
+
 def _check_version(esmfversion, esmpyversion):
     """
     Check the ESMF version (from ESMF_VERSION_STRING in the esmf.mk file) against the
diff --git a/src/addon/esmpy/src/esmpy/test/test_interface/test_loadESMF_helpers.py b/src/addon/esmpy/src/esmpy/test/test_interface/test_loadESMF_helpers.py
index 6b9cf38b14..b574066cd4 100644
--- a/src/addon/esmpy/src/esmpy/test/test_interface/test_loadESMF_helpers.py
+++ b/src/addon/esmpy/src/esmpy/test/test_interface/test_loadESMF_helpers.py
@@ -2,10 +2,14 @@
 Unit tests of loadESMF_helpers.py
 """
 
+import os
+import tempfile
+
 import pytest
 import warnings
 
-from esmpy.interface.loadESMF_helpers import _check_version
+from esmpy.interface.loadESMF_helpers import (_check_version, _find_esmf_mk,
+                                              _esmf_mk_is_bundled)
 from esmpy.test.base import TestBase
 from esmpy.util.exceptions import VersionWarning, VersionMismatch
 
@@ -89,3 +93,112 @@ def test_check_version_release_vs_beta(self):
         with pytest.raises(VersionMismatch):
             _check_version("8.9.0", "8.9.0b0")
 
+    def test_find_esmf_mk_env_var_takes_precedence(self):
+        """
+        Given ESMFMKFILE set in the environment,
+        when _find_esmf_mk is called,
+        then that value is returned verbatim (even if the file does not exist),
+        preserving the historical behavior.
+        """
+        environ = {"ESMFMKFILE": "/some/explicit/esmf.mk"}
+        result = _find_esmf_mk(environ, sys_prefix="/unused", package_dir="/unused")
+        assert result == "/some/explicit/esmf.mk"
+
+    def test_find_esmf_mk_bundled_in_package(self):
+        """
+        Given no ESMFMKFILE and an esmf.mk bundled inside the esmpy package,
+        when _find_esmf_mk is called,
+        then the bundled esmf.mk path is returned.
+        """
+        with tempfile.TemporaryDirectory() as tmp:
+            pkg = os.path.join(tmp, "esmpy")
+            bundled = os.path.join(pkg, "_esmf", "lib", "esmf.mk")
+            os.makedirs(os.path.dirname(bundled))
+            open(bundled, "w").close()
+            result = _find_esmf_mk({}, sys_prefix=tmp, package_dir=pkg)
+            assert result == bundled
+
+    def test_find_esmf_mk_bundled_preferred_over_conda(self):
+        """
+        Given both a bundled esmf.mk and a conda-style sys.prefix/lib/esmf.mk,
+        when _find_esmf_mk is called,
+        then the bundled copy wins.
+        """
+        with tempfile.TemporaryDirectory() as tmp:
+            pkg = os.path.join(tmp, "esmpy")
+            bundled = os.path.join(pkg, "_esmf", "lib", "esmf.mk")
+            conda = os.path.join(tmp, "lib", "esmf.mk")
+            for path in (bundled, conda):
+                os.makedirs(os.path.dirname(path))
+                open(path, "w").close()
+            result = _find_esmf_mk({}, sys_prefix=tmp, package_dir=pkg)
+            assert result == bundled
+
+    def test_find_esmf_mk_conda_prefix(self):
+        """
+        Given no ESMFMKFILE and only a conda-style sys.prefix/lib/esmf.mk,
+        when _find_esmf_mk is called,
+        then that path is returned.
+        """
+        with tempfile.TemporaryDirectory() as tmp:
+            conda = os.path.join(tmp, "lib", "esmf.mk")
+            os.makedirs(os.path.dirname(conda))
+            open(conda, "w").close()
+            pkg = os.path.join(tmp, "esmpy")  # no bundled esmf.mk here
+            result = _find_esmf_mk({}, sys_prefix=tmp, package_dir=pkg)
+            assert result == conda
+
+    def test_find_esmf_mk_not_found_raises(self):
+        """
+        Given no ESMFMKFILE and no esmf.mk in any known location,
+        when _find_esmf_mk is called,
+        then an ImportError is raised.
+        """
+        with tempfile.TemporaryDirectory() as tmp:
+            with pytest.raises(ImportError):
+                _find_esmf_mk({}, sys_prefix=tmp,
+                              package_dir=os.path.join(tmp, "esmpy"))
+
+    def test_esmf_mk_is_bundled_true(self):
+        """
+        Given an esmf.mk located inside the esmpy package directory,
+        when _esmf_mk_is_bundled is called,
+        then it returns True.
+        """
+        with tempfile.TemporaryDirectory() as tmp:
+            pkg = os.path.join(tmp, "esmpy")
+            mk = os.path.join(pkg, "_esmf", "lib", "esmf.mk")
+            os.makedirs(os.path.dirname(mk))
+            open(mk, "w").close()
+            assert _esmf_mk_is_bundled(mk, pkg) is True
+
+    def test_esmf_mk_is_bundled_false_outside_package(self):
+        """
+        Given an esmf.mk outside the esmpy package (conda/source install),
+        when _esmf_mk_is_bundled is called,
+        then it returns False.
+        """
+        with tempfile.TemporaryDirectory() as tmp:
+            pkg = os.path.join(tmp, "esmpy")
+            os.makedirs(pkg)
+            mk = os.path.join(tmp, "lib", "esmf.mk")
+            os.makedirs(os.path.dirname(mk))
+            open(mk, "w").close()
+            assert _esmf_mk_is_bundled(mk, pkg) is False
+
+    def test_esmf_mk_is_bundled_false_for_sibling_prefix(self):
+        """
+        Given a package dir and an esmf.mk under a sibling directory whose path
+        merely starts with the package dir's name (e.g. esmpy vs esmpy-data),
+        when _esmf_mk_is_bundled is called,
+        then it returns False (the separator guard prevents a false match).
+        """
+        with tempfile.TemporaryDirectory() as tmp:
+            pkg = os.path.join(tmp, "esmpy")
+            sibling = os.path.join(tmp, "esmpy-data")
+            os.makedirs(pkg)
+            os.makedirs(sibling)
+            mk = os.path.join(sibling, "esmf.mk")
+            open(mk, "w").close()
+            assert _esmf_mk_is_bundled(mk, pkg) is False
+