diff --git a/ext/mbstring/php_unicode.h b/ext/mbstring/php_unicode.h
index 36a6955830a..a21191250c0 100644
--- a/ext/mbstring/php_unicode.h
+++ b/ext/mbstring/php_unicode.h
@@ -66,8 +66,8 @@
 #define UC_AL 32 /* Arabic Letter              */
 
 /* Merged property categories */
-#define UC_C 33
-#define UC_P 34
+#define UC_C 33 /* Control */
+#define UC_P 34 /* Punctuation */
 
 /* Derived properties from DerivedCoreProperties.txt */
 #define UC_CASED          35