diff --git a/Mac/Modules/macmodule.c b/Mac/Modules/macmodule.c
index d553f30..9674ab7 100644
--- a/Mac/Modules/macmodule.c
+++ b/Mac/Modules/macmodule.c
@@ -586,6 +586,8 @@
 }
 
 #ifdef USE_MALLOC_DEBUG
+void *mstats(char *);
+
 static PyObject *
 mac_mstats(self, args)
 	PyObject*self;