diff --git a/collects/macro-debugger/model/deriv-parser.ss b/collects/macro-debugger/model/deriv-parser.ss
index 029041c..8751731 100644
--- a/collects/macro-debugger/model/deriv-parser.ss
+++ b/collects/macro-debugger/model/deriv-parser.ss
@@ -191,8 +191,8 @@
 
     (NotReallyLocalAction
      ;; called 'expand' (not 'local-expand') within transformer
-     [(start (? EE))
-      #f])
+     [(start (? EE)) #f]
+     [(start (? CheckImmediateMacro)) #f])
 
     (Prim
      (#:args e1 e2 rs)
diff --git a/collects/macro-debugger/view/step-display.ss b/collects/macro-debugger/view/step-display.ss
index 7c80955..5894078 100644
--- a/collects/macro-debugger/view/step-display.ss
+++ b/collects/macro-debugger/view/step-display.ss
@@ -107,13 +107,13 @@
              (show-poststep step binders shift-table)]))
 
     (define/public (add-syntax stx
-                               #:binders binders
+                               #:binders [binders #f]
                                #:shift-table [shift-table #f]
-                               #:definites definites)
+                               #:definites [definites null])
       (send sbview add-syntax stx
             #:binder-table binders
             #:shift-table shift-table
-            #:definites (or definites null)))
+            #:definites definites))
 
     (define/public (add-final stx error
                               #:binders binders
@@ -124,7 +124,7 @@
         (send sbview add-syntax stx
               #:binder-table binders
               #:shift-table shift-table
-              #:definites (or definites null)))
+              #:definites definites))
       (when error
         (add-error error)))
 
diff --git a/collects/macro-debugger/view/term-record.ss b/collects/macro-debugger/view/term-record.ss
index a963906..e924a05 100644
--- a/collects/macro-debugger/view/term-record.ss
+++ b/collects/macro-debugger/view/term-record.ss
@@ -274,7 +274,7 @@
 
     ;; display-initial-term : -> void
     (define/public (display-initial-term)
-      (send displayer add-syntax (wderiv-e1 deriv) #f null))
+      (send displayer add-syntax (wderiv-e1 deriv)))
 
     ;; display-final-term : -> void
     (define/public (display-final-term)