diff --git a/collects/web-server/lang/abort-resume.ss b/collects/web-server/lang/abort-resume.ss
index a0f1c69db6..a6fb1530eb 100644
--- a/collects/web-server/lang/abort-resume.ss
+++ b/collects/web-server/lang/abort-resume.ss
@@ -35,14 +35,12 @@
 (define web-prompt (make-continuation-prompt-tag 'web)) 
 
 (define (current-saved-continuation-marks-and key val)
-  (list* (cons key val)
-         (filter (lambda (k*v) (not (equal? key (car k*v))))
-                 (let-values ([(current)
-                               (continuation-mark-set->list (current-continuation-marks web-prompt)
-                                                            the-save-cm-key)])
-                   (if (empty? current)
-                       empty
-                       (first current))))))
+  (define c
+    (continuation-mark-set->list (current-continuation-marks web-prompt)
+                               the-save-cm-key))
+  (if (empty? c)
+      (make-immutable-hash (list (cons key val)))
+      (hash-set (first c) key val)))
 
 ;; current-continuation-as-list: -> (listof value)
 ;; check the safety marks and return the list of marks representing the continuation
@@ -73,6 +71,11 @@
      (with-continuation-mark cm-key cm-val
        (with-continuation-marks cms thnk))]))
 
+(define (with-continuation-marks/hash cms thnk)
+  (with-continuation-marks 
+   (hash-map cms cons)
+   thnk))
+
 ;; resume: (listof (value -> value)) value -> value
 ;; resume a computation given a value and list of frame procedures
 (define (resume frames val)
@@ -89,7 +92,7 @@
                           f)]
        [(vector #f cms)
         (with-continuation-mark the-save-cm-key cms
-          (with-continuation-marks cms (lambda () (resume fs val))))]
+          (with-continuation-marks/hash cms (lambda () (resume fs val))))]
        [(vector f cms)
         (resume (list* (vector f #f) (vector #f cms) fs) val)])]))
 
@@ -104,7 +107,7 @@
        [(vector f #f)
         (rebuild-cms fs thunk)]
        [(vector f cms)
-        (with-continuation-marks cms (lambda () (rebuild-cms fs thunk)))])]))
+        (with-continuation-marks/hash cms (lambda () (rebuild-cms fs thunk)))])]))
 
 (define (abort/cc thunk)
   (call-with-continuation-prompt
diff --git a/collects/web-server/tests/lang/abort-resume-test.ss b/collects/web-server/tests/lang/abort-resume-test.ss
index f0be4ce575..35d754f469 100644
--- a/collects/web-server/tests/lang/abort-resume-test.ss
+++ b/collects/web-server/tests/lang/abort-resume-test.ss
@@ -19,36 +19,42 @@
      "Easy"
      (check-equal? (abort/cc
                     (lambda () (current-saved-continuation-marks-and 'k1 'v1)))
-                   (list (cons 'k1 'v1))))
+                   (make-immutable-hash (list (cons 'k1 'v1)))))
     
     (test-case
      "Preserve"
      (check-equal? (abort/cc
                     (lambda () 
-                      (with-continuation-mark the-save-cm-key (list (cons 'k2 'v2))
+                      (with-continuation-mark the-save-cm-key (make-immutable-hash (list (cons 'k2 'v2)))
                         (current-saved-continuation-marks-and 'k1 'v1))))
-                   (list (cons 'k1 'v1)
-                         (cons 'k2 'v2))))
+                   (make-immutable-hash 
+                    (list (cons 'k1 'v1)
+                         (cons 'k2 'v2)))))
     
     (test-case
      "Update"
      (check-equal? (abort/cc
                     (lambda () 
-                      (with-continuation-mark the-save-cm-key (list (cons 'k2 'v2) (cons 'k1 'v3))
+                      (with-continuation-mark the-save-cm-key 
+                        (make-immutable-hash (list (cons 'k2 'v2) (cons 'k1 'v3)))
                         (current-saved-continuation-marks-and 'k1 'v1))))
-                   (list (cons 'k1 'v1)
-                         (cons 'k2 'v2))))
+                   (make-immutable-hash 
+                    (list (cons 'k1 'v1)
+                         (cons 'k2 'v2)))))
     
     (test-case
      "Double"
      (check-equal? (abort/cc
                     (lambda () 
-                      (with-continuation-mark the-save-cm-key (list (cons 'k3 'v1) (cons 'k4 'v0))
+                      (with-continuation-mark the-save-cm-key 
+                        (make-immutable-hash (list (cons 'k3 'v1) (cons 'k4 'v0)))
                         ((lambda (x) x)
-                         (with-continuation-mark the-save-cm-key (list (cons 'k2 'v2) (cons 'k1 'v3))
+                         (with-continuation-mark the-save-cm-key 
+                           (make-immutable-hash (list (cons 'k2 'v2) (cons 'k1 'v3)))
                            (current-saved-continuation-marks-and 'k1 'v1))))))
-                   (list (cons 'k1 'v1)
-                         (cons 'k2 'v2)))))
+                   (make-immutable-hash 
+                    (list (cons 'k1 'v1)
+                         (cons 'k2 'v2))))))
    
    (test-suite 
     "activation-record-list"
@@ -156,9 +162,9 @@
        (check-equal? (abort/cc
                       (lambda ()
                         (let/ec esc 
-                          (resume (list (vector f (list (cons 3 4) (cons 1 2))) 
-                                        (vector g (list (cons 5 6)))
-                                        (vector esc (list (cons 7 8)))
+                          (resume (list (vector f (make-immutable-hash (list (cons 3 4) (cons 1 2)))) 
+                                        (vector g (make-immutable-hash (list (cons 5 6))))
+                                        (vector esc (make-immutable-hash (list (cons 7 8))))
                                         (vector (lambda _
                                                   (continuation-mark-set->list*
                                                    (current-continuation-marks)
@@ -179,14 +185,14 @@
                       (lambda ()
                         (let/ec esc 
                           (set-box! esc-b esc)
-                          (resume (list (vector f (list (cons 3 4) (cons 1 2))) 
-                                        (vector g (list (cons 5 6)))
-                                        (vector esc (list (cons 7 8)))
+                          (resume (list (vector f (make-immutable-hash (list (cons 3 4) (cons 1 2)))) 
+                                        (vector g (make-immutable-hash (list (cons 5 6))))
+                                        (vector esc (make-immutable-hash (list (cons 7 8))))
                                         (vector capture #f))
                                   (list 42)))))
-                     (list (vector f (list (cons 3 4) (cons 1 2))) 
-                           (vector g (list (cons 5 6)))
-                           (vector (unbox esc-b) (list (cons 7 8))))))))
+                     (list (vector f (make-immutable-hash (list (cons 3 4) (cons 1 2)))) 
+                           (vector g (make-immutable-hash (list (cons 5 6))))
+                           (vector (unbox esc-b) (make-immutable-hash (list (cons 7 8)))))))))
    
    ; XXX test kont   
    
@@ -198,4 +204,7 @@
    
    ; XXX test dispatch
    
-   ))
\ No newline at end of file
+   ))
+
+(require (planet "graphical-ui.ss" ("schematics" "schemeunit.plt" 2)))
+(test/graphical-ui abort-resume-tests)