diff --git a/Modules/cstubs b/Modules/cstubs
index 04f4578ff7a..d8f2d90c1bf 100644
--- a/Modules/cstubs
+++ b/Modules/cstubs
@@ -1336,3 +1336,4 @@ void pixmode		long s long s
 # New in IRIX 4.0
 #
 long qgetfd
+void dither		long s