diff --git a/unit_tests/unit_test_rules.mk b/unit_tests/unit_test_rules.mk
index 4fb38060ab..10f0690ffb 100644
--- a/unit_tests/unit_test_rules.mk
+++ b/unit_tests/unit_test_rules.mk
@@ -69,6 +69,7 @@ ifeq ($(USE_CPPOPT),)
 endif
 
 # Enable address sanitizer for C++ files, but not on Windows since x86_64-w64-mingw32-g++ doesn't support it.
+# only c++ because lua does some things asan doesn't like, but don't actually cause overruns.
 ifeq ($(SANITIZE),yes)
 	ifeq ($(IS_MAC),yes)
 		USE_CPPOPT += -fsanitize=address