diff --git a/Objects/obmalloc.c b/Objects/obmalloc.c
index f409ecd..e5ad0bc 100644
--- a/Objects/obmalloc.c
+++ b/Objects/obmalloc.c
@@ -695,7 +695,7 @@
    to supply a single place to set a breakpoint.
 */
 static void
-bumpserialno()
+bumpserialno(void)
 {
 	++serialno;
 }