diff --git a/collects/racket/draw/private/bitmap-dc.rkt b/collects/racket/draw/private/bitmap-dc.rkt
index 469508cb37..8aa16dbad5 100644
--- a/collects/racket/draw/private/bitmap-dc.rkt
+++ b/collects/racket/draw/private/bitmap-dc.rkt
@@ -50,6 +50,7 @@
                 (exact->inexact (send bm get-height)))))
 
     (define/override (get-cr) c)
+    (define/override (release-cr cr) (when bm (send bm drop-alpha-s)))
 
     (define/override (end-cr) (void))
 
diff --git a/collects/racket/draw/private/bitmap.rkt b/collects/racket/draw/private/bitmap.rkt
index 13114daf0f..da99da0d02 100644
--- a/collects/racket/draw/private/bitmap.rkt
+++ b/collects/racket/draw/private/bitmap.rkt
@@ -190,7 +190,7 @@
     ;; Use for non-alpha color bitmaps when they are used as a mask:
     (define alpha-s #f)
     (define alpha-s-up-to-date? #f)
-    (define/private (drop-alpha-s)
+    (define/public (drop-alpha-s)
       (set! alpha-s-up-to-date? #f)
       (when alpha-s
         (let ([s2 alpha-s])
@@ -681,7 +681,8 @@
        [(and set-alpha?
              (not alpha-channel?))
         ;; Set alphas:
-        (set-alphas-as-mask x y w h bstr (* 4 w) 0)]))
+        (set-alphas-as-mask x y w h bstr (* 4 w) 0)])
+      (drop-alpha-s))
     
     (define/public (get-alphas-as-mask x y w h bstr)
       (let ([data (cairo_image_surface_get_data (if (or b&w? alpha-channel?)
diff --git a/collects/racket/draw/private/local.rkt b/collects/racket/draw/private/local.rkt
index c3cfeea2c4..7987888e63 100644
--- a/collects/racket/draw/private/local.rkt
+++ b/collects/racket/draw/private/local.rkt
@@ -12,6 +12,7 @@
   get-cairo-alpha-surface
   release-bitmap-storage
   get-bitmap-gl-context
+  drop-alpha-s
 
   ;; bitmap-dc%
   internal-get-bitmap
diff --git a/collects/tests/gracket/dc.rktl b/collects/tests/gracket/dc.rktl
index cfff7e84ee..10ea7d6b4b 100644
--- a/collects/tests/gracket/dc.rktl
+++ b/collects/tests/gracket/dc.rktl
@@ -235,7 +235,7 @@
                255 0 0 0
                255 255 255 255))
   (send u set-loaded-mask mu)
-  (define (try-draw nonce-color b&w?)
+  (define (try-draw nonce-color b&w? changed?)
     (let* ((bm (make-object bitmap% 2 2 b&w?))
            (dc (make-object bitmap-dc% bm)))
       (send dc clear)
@@ -254,15 +254,33 @@
                          0 255 255 255
                          0 255 255 255
                          0 255 255 255)
-                  (bytes 255 100 0 0
-                         255 255 255 255
-                         255 255 255 255
-                         255 255 255 255))
+                  (if changed?
+                      (bytes 255 255 255 255
+                             255 0 0 0
+                             255 255 255 255
+                             255 255 255 255)
+                      (bytes 255 100 0 0
+                             255 255 255 255
+                             255 255 255 255
+                             255 255 255 255)))
               'masked-draw
               s))))
-  (try-draw (make-object color% "green") #f)
-  (try-draw (make-object color%) #f)
-  (try-draw (make-object color%) #t))
+  (try-draw (make-object color% "green") #f #f)
+  (try-draw (make-object color%) #f #f)
+  (try-draw (make-object color%) #t #f)
+  (send mu set-argb-pixels 0 0 2 2
+        (bytes 255 255 255 255
+               255 0 0 0
+               255 255 255 255
+               255 0 0 0))
+  (try-draw (make-object color%) #f #t)
+  (let ([dc (make-object bitmap-dc% mu)])
+    (send dc erase)
+    (send dc set-pen "white" 1 'transparent)
+    (send dc set-brush "black" 'solid)
+    (send dc draw-rectangle 0 0 1 1)
+    (send dc set-bitmap #f))
+  (try-draw (make-object color%) #f #f))
 
 ;; ----------------------------------------