diff --git a/collects/mred/mred.ss b/collects/mred/mred.ss
index 679a58f1..e556274a 100644
--- a/collects/mred/mred.ss
+++ b/collects/mred/mred.ss
@@ -4879,7 +4879,7 @@
 	  (send wx get-canvas-background)))]
 
       [set-resize-corner (lambda (on?)
-			   (send wx set-resize-corner))])
+			   (send wx set-resize-corner on?))])
     (private-field
       [wx #f])
     (sequence