diff --git a/collects/drscheme/private/rep.ss b/collects/drscheme/private/rep.ss
index 3670214c82..e1e7a5cc6a 100644
--- a/collects/drscheme/private/rep.ss
+++ b/collects/drscheme/private/rep.ss
@@ -1545,7 +1545,10 @@ TODO
           
           (super-new)
           (auto-wrap #t)
-          (set-styles-sticky #f)))
+          (set-styles-sticky #f)
+
+	  (inherit set-max-undo-history)
+	  (set-max-undo-history 'forever)))
       
       (define input-delta (make-object style-delta%))
       (send input-delta set-delta-foreground (make-object color% 0 150 0))
diff --git a/collects/drscheme/private/unit.ss b/collects/drscheme/private/unit.ss
index 258fb62426..f1fe791ebb 100644
--- a/collects/drscheme/private/unit.ss
+++ b/collects/drscheme/private/unit.ss
@@ -567,7 +567,7 @@ module browser threading seems wrong.
             (super-new)
 
 	    (inherit set-max-undo-history)
-	    (set-max-undo-history 5000))))
+	    (set-max-undo-history 'forever))))