diff --git a/collects/stepper/private/annotate.ss b/collects/stepper/private/annotate.ss
index 2e4c8c5ddb..5a2a69a785 100644
--- a/collects/stepper/private/annotate.ss
+++ b/collects/stepper/private/annotate.ss
@@ -1116,9 +1116,6 @@
         [(require module-name) exp]
         ; the 'dynamic-require' form is used by the actual expander 
         
-        ;; RIGHT HERE, basically: the test harness breaks because of multiple definitions of identifiers. Probably we want
-        ;; to mangle the output of run-teaching-program so that the module is required with some kind of temporary prefix?
-        
         [(let-values ([(done-already?) . rest1])
            (#%plain-app dynamic-wind
                   void
@@ -1192,13 +1189,15 @@
              [(begin .  bodies)
               #`(begin #,@(map annotate/module-top-level (syntax->list #`bodies)))]
              [(#%plain-app call-with-values (#%plain-lambda () body) print-values)
-              #`(call-with-values 
-                 (lambda () #,(top-level-annotate/inner (top-level-rewrite #`body) exp #f))
-                 (lambda vals
-                   (begin
-                     (#,exp-finished-break (list (list #,(lambda () exp) #f (lambda () vals))))
-                     (call-with-values (lambda () vals)
-                                       print-values))))]
+              (stepper-recertify 
+               #`(call-with-values 
+                  (lambda () #,(top-level-annotate/inner (top-level-rewrite #`body) exp #f))
+                  (lambda vals
+                    (begin
+                      (#,exp-finished-break (list (list #,(lambda () exp) #f (lambda () vals))))
+                      (call-with-values (lambda () vals)
+                                        print-values))))
+               exp)]
              [any
               (stepper-syntax-property exp 'stepper-test-suite-hint)
               (top-level-annotate/inner (top-level-rewrite exp) exp #f)]
diff --git a/collects/stepper/private/marks.ss b/collects/stepper/private/marks.ss
index f4787574ae..ad416445e2 100644
--- a/collects/stepper/private/marks.ss
+++ b/collects/stepper/private/marks.ss
@@ -1,4 +1,4 @@
-(module marks mzscheme
+(module marks scheme/base
 
   (require mzlib/list
 	   mzlib/contract
@@ -38,10 +38,10 @@
    #;lookup-binding-list
    debug-key
    extract-mark-list
-   (struct normal-breakpoint-info (mark-list kind))
-   (struct error-breakpoint-info (message))
-   (struct breakpoint-halt ())
-   (struct expression-finished (returned-value-list)))
+   (struct-out normal-breakpoint-info)
+   (struct-out error-breakpoint-info)
+   (struct-out breakpoint-halt)
+   (struct-out expression-finished))
   
   ; BREAKPOINT STRUCTURES
   
@@ -72,7 +72,7 @@
   
   ; see module top for type
   (define (make-full-mark location label bindings)
-    (datum->syntax-object #'here `(lambda () (,(make-make-full-mark-varargs location label bindings)
+    (datum->syntax #'here `(lambda () (,(make-make-full-mark-varargs location label bindings)
                                               ,@(map make-mark-binding-stx bindings)))))
   
   (define (mark-source mark)
@@ -109,7 +109,7 @@
   (define (display-mark mark)
     (apply
      string-append
-     (format "source: ~a\n" (syntax-object->datum (mark-source mark)))
+     (format "source: ~a\n" (syntax->datum (mark-source mark)))
      (format "label: ~a\n" (mark-label mark))
      (format "bindings:\n")
      (map (lambda (binding)
@@ -135,11 +135,11 @@
   
   (define (lookup-binding mark-list id)
     (mark-binding-value
-     (lookup-first-binding (lambda (id2) (module-identifier=? id id2)) 
+     (lookup-first-binding (lambda (id2) (free-identifier=? id id2)) 
                            mark-list 
                            (lambda ()
                              (error 'lookup-binding "variable not found in environment: ~a~n" (if (syntax? id) 
-                                                                                                  (syntax-object->datum id)
+                                                                                                  (syntax->datum id)
                                                                                                   id))))))
   
   (define (all-bindings mark)
diff --git a/collects/stepper/private/model.ss b/collects/stepper/private/model.ss
index 144814e275..e281a90fe4 100644
--- a/collects/stepper/private/model.ss
+++ b/collects/stepper/private/model.ss
@@ -36,20 +36,19 @@
 ;  late-let(x) : ERROR
 
 
-(module model mzscheme
-  (require mzlib/contract
-           mzlib/etc
+(module model scheme/base
+  (require scheme/contract
            scheme/match
-           mzlib/class
+           scheme/class
            scheme/list
-           (prefix a: "annotate.ss")
-           (prefix r: "reconstruct.ss")
+           (prefix-in a: "annotate.ss")
+           (prefix-in r: "reconstruct.ss")
            "shared.ss"
            "marks.ss"
            "model-settings.ss"
            "macro-unwind.ss"
            "lifting.ss"
-           (prefix test-engine: test-engine/scheme-tests)
+           (prefix-in test-engine: test-engine/scheme-tests)
            #;(file "/Users/clements/clements/scheme-scraps/eli-debug.ss")
            ;; for breakpoint display
            ;; (commented out to allow nightly testing)
@@ -156,7 +155,7 @@
     (define steps-received 0)
 
     (define break
-      (opt-lambda (mark-set break-kind [returned-value-list #f])
+      (lambda (mark-set break-kind [returned-value-list #f])
 
         (set! steps-received (+ steps-received 1))
         ;; have to be careful else this won't be looked up right away: