diff --git a/collects/stepper/private/model.ss b/collects/stepper/private/model.ss
index fb91862591..199db817f0 100644
--- a/collects/stepper/private/model.ss
+++ b/collects/stepper/private/model.ss
@@ -361,11 +361,12 @@
 (define-struct skipped-step ())
 (define the-skipped-step (make-skipped-step))
 
-;; produce a posn-info structure based on the information in a mark-list
+;; produce a posn-info structure or false based on the information in a mark-list
+;; mark-list->posn-info : (listof mark) -> (or/c posn-info? false?)
 (define (mark-list->posn-info mark-list)
   (let* ([first-mark-source (mark-source (car mark-list))]
          [posn (syntax-position first-mark-source)]
          [span (syntax-span first-mark-source)])
-    (unless posn
-      (error 'mark-list->posn-info "expected a syntax object with a syntax-position, got: ~v" (syntax->datum first-mark-source)))    
-    (make-posn-info posn span)))
+    (if posn
+        (make-posn-info posn span)
+        #f)))
diff --git a/collects/stepper/view-controller.ss b/collects/stepper/view-controller.ss
index 2a34f097e5..f44e990a39 100644
--- a/collects/stepper/view-controller.ss
+++ b/collects/stepper/view-controller.ss
@@ -68,7 +68,7 @@
   ;; possible values: #f, or a predicate on steps.
   (define stepper-is-waiting? (lambda (x) #t))
   
-  ;; hand-off-and-block : (-> text%? boolean? void?)
+  ;; hand-off-and-block : (-> text%? any (listof (or/c posn-info? false?)) void?)
   ;; hand-off-and-block generates a new semaphore, hands off a thunk to
   ;; drscheme's eventspace, and blocks on the new semaphore.  The thunk
   ;; adds the text% to the waiting queue, and checks to see if the
@@ -194,7 +194,8 @@
        (begin
             ;; each step has its own semaphore, so releasing one twice is
             ;; no problem.
-            (semaphore-post release-for-next-step)
+            (when release-for-next-step
+              (semaphore-post release-for-next-step))
             (when stepper-is-waiting?
               (error 'try-to-get-view
                      "try-to-get-view should not be reachable when already waiting for new step"))
@@ -327,7 +328,9 @@
   ;; en/dis-able-buttons : set enable & disable the stepper buttons,
   ;; based on view-controller state
   (define (en/dis-able-buttons)
-    (let* ([can-go-back? (and view (> view 0))])
+     ;; let's just leave all the buttons enabled...
+     (void)
+     #;(let* ([can-go-back? (and view (> view 0))])
       (send previous-button enable can-go-back?)
       (send previous-application-button enable can-go-back?)
       (send next-button