diff --git a/build-llvm.sh b/build-llvm.sh
index 9f21b71..c950cfa 100755
--- a/build-llvm.sh
+++ b/build-llvm.sh
@@ -71,6 +71,7 @@ while [ $# -gt 0 ]; do
         ;;
     --macos-native-tools)
         MACOS_NATIVE_TOOLS=1
+        unset CLEAN
         ;;
     --instrumented|--instrumented=*)
         INSTRUMENTED="${1#--instrumented}"