diff --git a/collects/racket/draw/private/bitmap-dc.rkt b/collects/racket/draw/private/bitmap-dc.rkt
index a04ed16e0a..2758407159 100644
--- a/collects/racket/draw/private/bitmap-dc.rkt
+++ b/collects/racket/draw/private/bitmap-dc.rkt
@@ -13,7 +13,7 @@
 
 (define bitmap-dc-backend%
   (class default-dc-backend%
-    (init [_bm #f])
+    (init [(_bm bitmap) #f])
     (inherit reset-cr)
 
     (define c #f)