diff --git a/collects/mrlib/gif.rkt b/collects/mrlib/gif.rkt
index 17448855db..4e26b1bbbf 100644
--- a/collects/mrlib/gif.rkt
+++ b/collects/mrlib/gif.rkt
@@ -1,94 +1,95 @@
+#lang racket/base
 
-(module gif scheme/base
-  (require scheme/gui/base
-           scheme/class
-           scheme/list
-           net/gifwrite
-           racket/contract)
-  
-  (provide write-gif)
-  
-  (define (force-bm bm) (if (procedure? bm) (bm) bm))
-  
-  (define (split-bytes b len offset)
-    (if (= offset (bytes-length b))
-        null
-        (cons (subbytes b offset (+ offset len))
-              (split-bytes b len (+ offset len)))))
-  
-  (define (write-gifs bms delay filename one-at-a-time? last-frame-delay loop?)
-    (let* ([init (force-bm (car bms))]
-           [w (send init get-width)]
-           [h (send init get-height)])
-      (let ([argb-thunks
-             (map (lambda (bm)
-                    (lambda ()
-                      (let ([bm (force-bm bm)]
-                            [argb (make-bytes (* w h 4) 255)])
-                        (send bm get-argb-pixels 0 0 w h argb)
-                        (let ([mask (send bm get-loaded-mask)])
-                          (when mask
-                            (send mask get-argb-pixels 0 0 w h argb #t)))
-                        argb)))
-                  (cons init (cdr bms)))])
-        (if one-at-a-time?
-            ;; Quantize individually, and stream the images through
+;; A library for creating gifs out of bitmap%s
+
+(require racket/gui/base
+         racket/class
+         racket/list
+         net/gifwrite
+         racket/contract)
+
+(provide write-gif)
+
+(define (force-bm bm) (if (procedure? bm) (bm) bm))
+
+(define (split-bytes b len offset)
+  (if (= offset (bytes-length b))
+      null
+      (cons (subbytes b offset (+ offset len))
+            (split-bytes b len (+ offset len)))))
+
+(define (write-gifs bms delay filename one-at-a-time? last-frame-delay loop?)
+  (let* ([init (force-bm (car bms))]
+         [w (send init get-width)]
+         [h (send init get-height)])
+    (let ([argb-thunks
+           (map (lambda (bm)
+                  (lambda ()
+                    (let ([bm (force-bm bm)]
+                          [argb (make-bytes (* w h 4) 255)])
+                      (send bm get-argb-pixels 0 0 w h argb)
+                      (let ([mask (send bm get-loaded-mask)])
+                        (when mask
+                          (send mask get-argb-pixels 0 0 w h argb #t)))
+                      argb)))
+                (cons init (cdr bms)))])
+      (if one-at-a-time?
+          ;; Quantize individually, and stream the images through
+          (call-with-output-file*
+           filename
+           (lambda (p)
+             (let* ([gif (gif-start p w h 0 #f)])
+               (when loop?
+                 (gif-add-loop-control gif 0))
+               (let ([last-argb-thunk (last argb-thunks)])
+                 (for-each (lambda (argb-thunk)
+                             (let-values ([(pixels colormap transparent)
+                                           (quantize (argb-thunk))])
+                               (when (or transparent delay)
+                                 (gif-add-control gif 'any #f (or delay 0) transparent))
+                               (gif-add-image gif 0 0 w h #f colormap pixels)
+                               (when (and last-frame-delay (eq? argb-thunk last-argb-thunk))
+                                 (gif-add-control gif 'any #f last-frame-delay transparent)
+                                 (gif-add-image gif 0 0 w h #f colormap pixels))))
+                           argb-thunks))
+               (gif-end gif))))
+          ;; Build images and quantize all at once:
+          (let-values ([(pixels colormap transparent)
+                        (quantize (apply bytes-append (map (lambda (t) (t)) argb-thunks)))])
             (call-with-output-file*
              filename
              (lambda (p)
-               (let* ([gif (gif-start p w h 0 #f)])
-                 (when loop?
+               (let* ([gif (gif-start p w h 0 colormap)])
+                 (when delay
                    (gif-add-loop-control gif 0))
-                 (let ([last-argb-thunk (last argb-thunks)])
-                   (for-each (lambda (argb-thunk)
-                               (let-values ([(pixels colormap transparent)
-                                             (quantize (argb-thunk))])
-                                 (when (or transparent delay)
-                                   (gif-add-control gif 'any #f (or delay 0) transparent))
-                                 (gif-add-image gif 0 0 w h #f colormap pixels)
-                                 (when (and last-frame-delay (eq? argb-thunk last-argb-thunk))
-                                   (gif-add-control gif 'any #f last-frame-delay transparent)
-                                   (gif-add-image gif 0 0 w h #f colormap pixels))))
-                             argb-thunks))
-                 (gif-end gif))))
-            ;; Build images and quantize all at once:
-            (let-values ([(pixels colormap transparent)
-                          (quantize (apply bytes-append (map (lambda (t) (t)) argb-thunks)))])
-              (call-with-output-file*
-               filename
-               (lambda (p)
-                 (let* ([gif (gif-start p w h 0 colormap)])
-                   (when delay
-                     (gif-add-loop-control gif 0))
-                   (let* ([pixelss (split-bytes pixels (* w h) 0)]
-                          [last-pixels (last pixelss)])
-                     (for-each (lambda (pixels)
-                                 (when (or transparent delay)
-                                   (gif-add-control gif 'any #f (or delay 0) transparent))
-                                 (gif-add-image gif 0 0 w h #f #f pixels)
-                                 (when (and last-frame-delay (eq? pixels last-pixels))
-                                   (gif-add-control gif 'any #f last-frame-delay transparent)
-                                   (gif-add-image gif 0 0 w h #f colormap pixels)))
-                               pixelss))
-                   (gif-end gif)))))))))
-  
-  (define (write-gif bm filename)
-    (write-gifs (list bm) #f filename #f #f #f))
-  
-  (provide/contract
-   [write-animated-gif 
-    (->i ((bms (and/c (listof (or/c (is-a?/c bitmap%) (-> (is-a?/c bitmap%)))) pair?))
-          (delay (integer-in 0 4294967295))
-          (filename (or/c path? string?)))
-         (#:one-at-a-time? (one-at-a-time? any/c)
-          #:last-frame-delay (last-frame-delay (or/c (integer-in 0 4294967295) false/c))
-          #:loop? (Loop? (delay) (lambda (x) (and delay #t))))
-         any)])
-         
-  (define (write-animated-gif bms delay filename 
-                              #:one-at-a-time? [one-at-a-time? #f]
-                              #:last-frame-delay [last-frame-delay #f]
-                              #:loop? [loop? (and delay #t)])
-    (write-gifs bms delay filename one-at-a-time? last-frame-delay loop?))
-  
-  )
+                 (let* ([pixelss (split-bytes pixels (* w h) 0)]
+                        [last-pixels (last pixelss)])
+                   (for-each (lambda (pixels)
+                               (when (or transparent delay)
+                                 (gif-add-control gif 'any #f (or delay 0) transparent))
+                               (gif-add-image gif 0 0 w h #f #f pixels)
+                               (when (and last-frame-delay (eq? pixels last-pixels))
+                                 (gif-add-control gif 'any #f last-frame-delay transparent)
+                                 (gif-add-image gif 0 0 w h #f colormap pixels)))
+                             pixelss))
+                 (gif-end gif)))))))))
+
+(define (write-gif bm filename)
+  (write-gifs (list bm) #f filename #f #f #f))
+
+(provide/contract
+ [write-animated-gif
+  (->i ((bms (and/c (listof (or/c (is-a?/c bitmap%) (-> (is-a?/c bitmap%)))) pair?))
+        (delay (integer-in 0 4294967295))
+        (filename (or/c path? string?)))
+       (#:one-at-a-time? (one-at-a-time? any/c)
+        #:last-frame-delay (last-frame-delay (or/c (integer-in 0 4294967295) false/c))
+        #:loop? (Loop? (delay) (lambda (x) (and delay #t))))
+       any)])
+
+(define (write-animated-gif bms delay filename
+                            #:one-at-a-time? [one-at-a-time? #f]
+                            #:last-frame-delay [last-frame-delay #f]
+                            #:loop? [loop? (and delay #t)])
+  (write-gifs bms delay filename one-at-a-time? last-frame-delay loop?))
+