diff --git a/MY-BASIC Quick Reference.pdf b/MY-BASIC Quick Reference.pdf
index 351b5f8..18b8b76 100644
Binary files a/MY-BASIC Quick Reference.pdf and b/MY-BASIC Quick Reference.pdf differ
diff --git a/core/my_basic.c b/core/my_basic.c
index 130faa9..12a3255 100755
--- a/core/my_basic.c
+++ b/core/my_basic.c
@@ -90,7 +90,9 @@ extern "C" {
 #define _NO_EAT_COMMA 2
 
 #if (defined _DEBUG && !defined NDEBUG)
-#	define _MB_ENABLE_ALLOC_STAT
+#   ifndef _MB_ENABLE_ALLOC_STAT
+#       define _MB_ENABLE_ALLOC_STAT
+#   endif /* _MB_ENABLE_ALLOC_STAT */
 #endif /* (defined _DEBUG && !defined NDEBUG) */
 
 /* Helper */