diff --git a/preprocessor.py b/preprocessor.py
index e9af8a34..1e113000 100755
--- a/preprocessor.py
+++ b/preprocessor.py
@@ -162,6 +162,9 @@ if __name__ == '__main__':
 #define NAMESPACE_LIST(NS,KLASS) NS::KLASS,
 
 
+#define APPEND_COMMA(X) X,
+
+
 #define STRINGIZE_DETAIL(x) #x
 #define STRINGIZE(x) STRINGIZE_DETAIL(x)
 #define STRINGIZE_LIST(x) STRINGIZE(x),