diff --git a/collects/macro-debugger/model/reductions.rkt b/collects/macro-debugger/model/reductions.rkt
index 925d3f2..2eb58fb 100644
--- a/collects/macro-debugger/model/reductions.rkt
+++ b/collects/macro-debugger/model/reductions.rkt
@@ -1,5 +1,6 @@
 #lang racket/base
 (require racket/match
+         (for-syntax racket/base)
          "../util/eomap.rkt"
          "stx-util.rkt"
          "deriv-util.rkt"
@@ -34,9 +35,16 @@
 
 ;; Syntax
 
-(define-syntax-rule (match/count x . clauses)
+(define-syntax-rule (match/count x clause ...)
   (begin (sequence-number (add1 (sequence-number)))
-         (match x . clauses)))
+         (let ([v x])
+           (match v
+             clause ...
+             [_ (error 'match "failed to match ~e at line ~s" v (line-of x))]))))
+
+(define-syntax (line-of stx)
+  (syntax-case stx ()
+    [(line-of x) #`(quote #,(syntax-line #'x))]))
 
 ;; Derivations => Steps
 
@@ -472,7 +480,10 @@
         ;; Add remark step?
         ]]
     [(struct local-remark (contents))
-     (R [#:reductions (list (walk/talk 'remark contents))])]))
+     (R [#:reductions (list (walk/talk 'remark contents))])]
+
+    [#f
+     (R)]))
 
 ;; List : ListDerivation -> RST
 (define (List ld)
diff --git a/collects/macro-debugger/model/yacc-interrupted.rkt b/collects/macro-debugger/model/yacc-interrupted.rkt
index 9e8d2a5..944b9cc 100644
--- a/collects/macro-debugger/model/yacc-interrupted.rkt
+++ b/collects/macro-debugger/model/yacc-interrupted.rkt
@@ -1,6 +1,6 @@
 #lang racket/base
 (require (for-syntax racket/base
-                     unstable/syntax)
+                     racket/syntax)
          "yacc-ext.rkt")
 (provide ! ? !!
          define-production-splitter
diff --git a/collects/macro-debugger/syntax-browser/widget.rkt b/collects/macro-debugger/syntax-browser/widget.rkt
index fd75cdd..b84fddc 100644
--- a/collects/macro-debugger/syntax-browser/widget.rkt
+++ b/collects/macro-debugger/syntax-browser/widget.rkt
@@ -117,8 +117,8 @@
             (send -text change-style clickback-style a b)))))
 
     (define/public (add-syntax stx
-                               #:binders [binders #f]
-                               #:shift-table [shift-table #f]
+                               #:binders [binders '#hash()]
+                               #:shift-table [shift-table '#hash()]
                                #:definites [definites #f]
                                #:hi-colors [hi-colors null]
                                #:hi-stxss [hi-stxss null]
diff --git a/collects/macro-debugger/view/step-display.rkt b/collects/macro-debugger/view/step-display.rkt
index 51259a6..d2f6f7d 100644
--- a/collects/macro-debugger/view/step-display.rkt
+++ b/collects/macro-debugger/view/step-display.rkt
@@ -84,9 +84,9 @@
              (show-poststep step shift-table)]))
 
     (define/public (add-syntax stx
-                               #:binders [binders #f]
+                               #:binders [binders '#hash()]
                                #:definites [definites #f]
-                               #:shift-table [shift-table #f])
+                               #:shift-table [shift-table '#hash()])
       (send/i sbview sb:syntax-browser<%> add-syntax stx
               #:binders binders
               #:definites definites