diff --git a/include/rapidjson/schema.h b/include/rapidjson/schema.h
index 2713fb2..7493871 100644
--- a/include/rapidjson/schema.h
+++ b/include/rapidjson/schema.h
@@ -25,7 +25,7 @@
 #define RAPIDJSON_SCHEMA_USE_INTERNALREGEX 0
 #endif
 
-#if !RAPIDJSON_SCHEMA_USE_INTERNALREGEX && !defined(RAPIDJSON_SCHEMA_USE_STDREGEX) && (__cplusplus >=201103L || (defined(_MSC_VER) && _MSC_VER >= 1800))
+#if !RAPIDJSON_SCHEMA_USE_INTERNALREGEX && defined(RAPIDJSON_SCHEMA_USE_STDREGEX) && (__cplusplus >=201103L || (defined(_MSC_VER) && _MSC_VER >= 1800))
 #define RAPIDJSON_SCHEMA_USE_STDREGEX 1
 #else
 #define RAPIDJSON_SCHEMA_USE_STDREGEX 0