diff --git a/test/blackbox-tests/test-cases/pkg/portable-lockdirs/portable-lockdirs-platform-alternative-selection.t b/test/blackbox-tests/test-cases/pkg/portable-lockdirs/portable-lockdirs-platform-alternative-selection.t
new file mode 100644
index 00000000000..5a2ac3bd812
--- /dev/null
+++ b/test/blackbox-tests/test-cases/pkg/portable-lockdirs/portable-lockdirs-platform-alternative-selection.t
@@ -0,0 +1,70 @@
+A dependency disjunction may select different package names on different
+platforms. Preserve each platform's selection when generating a portable lock
+directory.
+
+  $ mkrepo
+  $ add_mock_repo_if_needed
+
+Define an implementation for each operating system:
+
+  $ mkpkg linux-impl <<'EOF'
+  > available: os = "linux"
+  > build: [
+  >   ["mkdir" "-p" share "%{lib}%/%{name}%"]
+  >   ["touch" "%{lib}%/%{name}%/META"]
+  > ]
+  > EOF
+
+  $ mkpkg macos-impl <<'EOF'
+  > available: os = "macos"
+  > build: [
+  >   ["mkdir" "-p" share "%{lib}%/%{name}%"]
+  >   ["touch" "%{lib}%/%{name}%/META"]
+  > ]
+  > EOF
+
+The common package accepts either implementation:
+
+  $ mkpkg foo <<'EOF'
+  > depends: [ "linux-impl" | "macos-impl" ]
+  > build: [
+  >   ["mkdir" "-p" share "%{lib}%/%{name}%"]
+  >   ["touch" "%{lib}%/%{name}%/META"]
+  > ]
+  > EOF
+
+  $ make_portable_lockdirs_project
+  $ dune pkg lock
+  Solution for dune.lock
+  
+  Dependencies common to all supported platforms:
+  - foo.0.0.1
+  
+  Additionally, some packages will only be built on specific platforms.
+  
+  arch = arm64; os = linux:
+  - linux-impl.0.0.1
+  
+  arch = arm64; os = macos:
+  - macos-impl.0.0.1
+  
+  arch = x86_64; os = linux:
+  - linux-impl.0.0.1
+  
+  arch = x86_64; os = macos:
+  - macos-impl.0.0.1
+
+The lock directory selects and builds only the appropriate implementation for
+each platform:
+
+  $ DUNE_CONFIG__OS=linux DUNE_CONFIG__ARCH=arm64 DUNE_CONFIG__OS_FAMILY=debian DUNE_CONFIG__OS_DISTRIBUTION=ubuntu DUNE_CONFIG__OS_VERSION=24.11 dune build
+  $ ls $pkg_root/ | censor
+  foo.0.0.1-$DIGEST1
+  linux-impl.0.0.1-$DIGEST2
+
+  $ dune clean
+
+  $ DUNE_CONFIG__OS=macos DUNE_CONFIG__ARCH=x86_64 DUNE_CONFIG__OS_FAMILY=homebrew DUNE_CONFIG__OS_DISTRIBUTION=homebrew DUNE_CONFIG__OS_VERSION=15.3.1 dune build
+  $ ls $pkg_root/ | censor
+  foo.0.0.1-$DIGEST1
+  macos-impl.0.0.1-$DIGEST2