diff --git a/scripts/build-futility.sh b/scripts/build-futility.sh
index 6344692..e1c6796 100755
--- a/scripts/build-futility.sh
+++ b/scripts/build-futility.sh
@@ -26,8 +26,9 @@
 ${NINJA_PROGRAM}
 popd
 
+HAVE_MACOS=0
 if [[ $(uname) == "Darwin" ]]; then
-  export HAVE_MACOS=1 
+  HAVE_MACOS=1 
 fi
 
 (