diff --git a/.ghci b/.ghci
new file mode 100644
index 00000000..93e78dd2
--- /dev/null
+++ b/.ghci
@@ -0,0 +1,13 @@
+-- Default `-Werror` flags that should be disabled in GHCi
+:set -Wno-error=identities
+:set -Wno-error=redundant-constraints
+:set -Wno-error=unused-imports
+
+-- Default warning flags that should be disabled in GHCi
+:set -Wno-unused-local-binds
+:set -Wno-unused-packages
+:set -Wno-unused-pattern-binds
+:set -Wno-unused-top-binds
+
+-- Set the GHCi prompt for "proto3-suite" sessions.
+:set prompt "proto3-suite> "
\ No newline at end of file
diff --git a/README.md b/README.md
index c7c89a40..2069ae2a 100644
--- a/README.md
+++ b/README.md
@@ -44,14 +44,15 @@ testing). From the root of this repository, run:
 
 ```bash
 $ nix-shell
+[nix-shell]$ cabal configure -f development
 [nix-shell]$ cabal build
 ```
 
-Once your source code compiles and you want to test, run this instead:
+To enable testing, configure `cabal` with `--enable-test` and (optionally) with the [`development`](./proto3-suite.cabal) flag to enable `-Werror`. Once your source code compiles and you want to test, run:
 
 ```bash
 $ nix-shell
-[nix-shell]$ cabal configure --enable-tests
+[nix-shell]$ cabal configure -f development --enable-tests
 [nix-shell]$ cabal build
 [nix-shell]$ cabal test
 ```
diff --git a/nix/overlays/haskell-packages.nix b/nix/overlays/haskell-packages.nix
index c7c6e613..e047f17c 100644
--- a/nix/overlays/haskell-packages.nix
+++ b/nix/overlays/haskell-packages.nix
@@ -140,6 +140,10 @@ in {
 
                   postPatch = (oldArgs.postPatch or "") + copyGeneratedCode + patchTestScripts;
 
+                  configureFlags = (oldArgs.configureFlags or []) ++ [
+                    "-fdevelopment"
+                  ];
+
                   testHaskellDepends =
                     (oldArgs.testHaskellDepends or [ ]) ++ [
                       haskellPackagesNew.proto3-suite-boot
diff --git a/proto3-suite.cabal b/proto3-suite.cabal
index 472dfc84..6c5b3fd1 100644
--- a/proto3-suite.cabal
+++ b/proto3-suite.cabal
@@ -44,6 +44,11 @@ flag attoparsec-aeson
   Manual:        False
     -- "Manual: False" to automatically skip "attoparsec-aeson" if it is not available
 
+flag development
+  description: Enable development-specific options.
+  default: False 
+  manual: true
+
 source-repository head
   type:     git
   location: https://github.com/awakesecurity/proto3-suite
@@ -53,6 +58,10 @@ common common
     BlockArguments ExplicitNamespaces DeriveDataTypeable DeriveGeneric
     ImportQualifiedPost ViewPatterns
 
+  if flag(development)
+    ghc-options:
+      -Werror
+
 library
   import: common
 
@@ -138,7 +147,7 @@ library
     build-depends:     attoparsec-aeson >= 2.2.0.0
   hs-source-dirs:      src
   default-language:    Haskell2010
-  ghc-options:         -O2 -Wall -Werror
+  ghc-options:         -O2 -Wall
 
 test-suite tests
   import:           common
@@ -239,7 +248,7 @@ executable compile-proto-file
                        , system-filepath
                        , text
                        , turtle
-  ghc-options:         -O2 -Wall -Werror
+  ghc-options:         -O2 -Wall
 
 executable canonicalize-proto-file
   import:              common
@@ -254,4 +263,4 @@ executable canonicalize-proto-file
                        , proto3-wire >= 1.4.6 && < 1.5
                        , system-filepath
                        , turtle
-  ghc-options:         -O2 -Wall -Werror
+  ghc-options:         -O2 -Wall