diff --git a/tcctest.c b/tcctest.c
index 2bec2ef..d9f565a 100644
--- a/tcctest.c
+++ b/tcctest.c
@@ -9,7 +9,7 @@
 /* only gcc 3 handles _Bool correctly */
 //#define BOOL_ISOC99
 
-//#define C99_MACROS
+#define C99_MACROS
 
 void string_test();
 void expr_test();