diff --git a/collects/macro-debugger/model/reductions-engine.ss b/collects/macro-debugger/model/reductions-engine.ss
index d916720..6335540 100644
--- a/collects/macro-debugger/model/reductions-engine.ss
+++ b/collects/macro-debugger/model/reductions-engine.ss
@@ -195,7 +195,7 @@
   ;; stumble/E : syntax(s) syntax exn -> Reduction
   (define (stumble/E focus Ee1 exn)
     (make-misstep (current-derivation) (big-context) 'error (context)
-                  focus Ee1 exn))
+                  (foci focus) Ee1 exn))
   
   ;; ------------------------------------