diff --git a/collects/hierlist/hierlist-unit.ss b/collects/hierlist/hierlist-unit.ss
index 7eecf22296..97679ab1d2 100644
--- a/collects/hierlist/hierlist-unit.ss
+++ b/collects/hierlist/hierlist-unit.ss
@@ -4,11 +4,17 @@
 	   (lib "class.ss")
 	   (lib "class100.ss")
 	   (lib "mred-sig.ss" "mred")
+	   (lib "include-bitmap.ss" "mrlib")
 	   "hierlist-sig.ss")
 
   (require (lib "list.ss")
 	   (lib "etc.ss"))
 
+  (define turn-up (include-bitmap "../icons/turn-up.png" 'png))
+  (define turn-down (include-bitmap "../icons/turn-down.png" 'png))
+  (define turn-up-click (include-bitmap "../icons/turn-up-click.png" 'png))
+  (define turn-down-click (include-bitmap "../icons/turn-down-click.png" 'png))
+
   (provide hierlist@)
   (define hierlist@
     (unit/sig hierlist^
@@ -27,17 +33,7 @@
       (define arrow-cursor (make-object cursor% 'arrow))
       
       (define-values (up-bitmap down-bitmap up-click-bitmap down-click-bitmap)
-	(with-handlers ([exn:fail? (lambda (x)
-				     (values
-				      (make-object bitmap% 10 10)
-				      (make-object bitmap% 10 10)
-				      (make-object bitmap% 10 10)
-				      (make-object bitmap% 10 10)))])
-	  (values
-	   (make-object bitmap% (build-path (collection-path "icons") "turn-up.png"))
-	   (make-object bitmap% (build-path (collection-path "icons") "turn-down.png"))
-	   (make-object bitmap% (build-path (collection-path "icons") "turn-up-click.png"))
-	   (make-object bitmap% (build-path (collection-path "icons") "turn-down-click.png")))))
+	(values turn-up turn-down turn-up-click turn-down-click))
 
       ;; Hack for implementing auto-wrapping items:
       (define arrow-size 0)
diff --git a/collects/mrlib/doc.txt b/collects/mrlib/doc.txt
index 401d5c713d..4ff6e573d2 100644
--- a/collects/mrlib/doc.txt
+++ b/collects/mrlib/doc.txt
@@ -130,13 +130,15 @@ program. The advantage of "inlining" the bitmap is that a stand-alone
 executable can be created that contains the bitmap and does not refer
 to the original image file.
 
-> (include-bitmap file-spec)                       SYNTAX
+> (include-bitmap file-spec)                               SYNTAX
+> (include-bitmap file-spec type-expr)                     SYNTAX
 
 The `file-spec' is the same as for MzLib's `include': a path string, a
-`build-path' form, or a `lib' form.
+`build-path' form, or a `lib' form. The `type-expr' should produce
+'unknown, 'unknown/mask, etc., and the default is 'unknown/mask.
 
-> (include-bitmap/relative-to source file-spec)    SYNTAX
+> (include-bitmap/relative-to source file-spec)            SYNTAX
+> (include-bitmap/relative-to source file-spec type-expr)  SYNTAX
 
 Analogous to `include-at/relative-to', though only a source is needed
 (no context).
-
diff --git a/collects/mrlib/include-bitmap.ss b/collects/mrlib/include-bitmap.ss
index 6b7d07f3e2..57d5d7e54d 100644
--- a/collects/mrlib/include-bitmap.ss
+++ b/collects/mrlib/include-bitmap.ss
@@ -10,7 +10,7 @@
   
   (define-syntax (-include-bitmap stx)
     (syntax-case stx ()
-      [(_ orig-stx source path-spec)
+      [(_ orig-stx source path-spec type)
        (let* ([c-file (resolve-path-spec #'path-spec #'source #'orig-stx #'build-path)]
 	      [content
 	       (with-handlers ([exn:fail?
@@ -28,22 +28,24 @@
 	 (with-syntax ([content content]
 		       [c-file (path->bytes c-file)])
 	   (syntax/loc stx
-	     (get-or-load-bitmap content c-file))))]))
+	     (get-or-load-bitmap content c-file type))))]))
 
   (define-syntax (include-bitmap/relative-to stx)
     (syntax-case stx ()
-      [(_ source path-spec) #`(-include-bitmap #,stx source path-spec)]))
+      [(_ source path-spec) #`(-include-bitmap #,stx source path-spec 'unknown/mask)]
+      [(_ source path-spec type) #`(-include-bitmap #,stx source path-spec type)]))
 
   (define-syntax (include-bitmap stx)
     (syntax-case stx ()
-      [(_ path-spec) #`(-include-bitmap #,stx #,stx path-spec)]))
+      [(_ path-spec) #`(-include-bitmap #,stx #,stx path-spec 'unknown/mask)]
+      [(_ path-spec type) #`(-include-bitmap #,stx #,stx path-spec type)]))
 
   ;; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
   ;; Run-time support
 
   (define cached (make-hash-table 'equal))
 
-  (define (get-or-load-bitmap content orig)
+  (define (get-or-load-bitmap content orig type)
     (hash-table-get cached content
 		    (lambda ()
 		      (let ([bm (let ([fn (make-temporary-file)])
@@ -53,7 +55,7 @@
 					(with-output-to-file fn
 					  (lambda () (display content))
 					  'truncate)
-					(make-object bitmap% fn 'unknown/mask))
+					(make-object bitmap% fn type))
 				      (lambda ()
 					(delete-file fn))))])
 			(unless (send bm ok?)