diff --git a/copilot-bluespec/CHANGELOG b/copilot-bluespec/CHANGELOG
index 5365300c..c17e42e1 100644
--- a/copilot-bluespec/CHANGELOG
+++ b/copilot-bluespec/CHANGELOG
@@ -1,3 +1,7 @@
+2025-12-04
+        * Disable building testsuite by default, use cabal flag `test-bluespec`
+          to enable. (#673)
+
 2025-11-07
         * Version bump (4.6). (#679)
         * Flip direction of interface inputs and outputs in Bluespec. (#677)
diff --git a/copilot-bluespec/copilot-bluespec.cabal b/copilot-bluespec/copilot-bluespec.cabal
index 975868ac..40ed3093 100644
--- a/copilot-bluespec/copilot-bluespec.cabal
+++ b/copilot-bluespec/copilot-bluespec.cabal
@@ -34,6 +34,11 @@ source-repository head
     type:       git
     location:   https://github.com/Copilot-Language/copilot-bluespec.git
 
+flag test-bluespec
+    description: Enable tests that require the Bluespec compiler (bsc)
+    default: False
+    manual: True
+
 library
   default-language        : Haskell2010
   hs-source-dirs          : src
@@ -98,3 +103,8 @@ test-suite tests
 
   ghc-options:
     -Wall
+
+  if flag(test-bluespec)
+    buildable: True
+  else
+    buildable: False