diff --git a/collects/mred/private/wx/cocoa/dc.rkt b/collects/mred/private/wx/cocoa/dc.rkt
index 0b821447..cb81eb3e 100644
--- a/collects/mred/private/wx/cocoa/dc.rkt
+++ b/collects/mred/private/wx/cocoa/dc.rkt
@@ -48,7 +48,9 @@
                    g)))))
 
     ;; Use a quartz bitmap so that text looks good:
-    (define/override (make-backing-bitmap w h) (make-object quartz-bitmap% w h))
+    (define trans? transparent?)
+    (define/override (make-backing-bitmap w h) 
+      (make-object quartz-bitmap% w h trans?))
     (define/override (can-combine-text? sz) #t)
 
     (define/override (get-backing-size xb yb)