diff --git a/collects/drracket/private/unit.rkt b/collects/drracket/private/unit.rkt
index f951e8220c..454077ae57 100644
--- a/collects/drracket/private/unit.rkt
+++ b/collects/drracket/private/unit.rkt
@@ -4571,7 +4571,7 @@ module browser threading seems wrong.
       
       (when (= 2 (length (send resizable-panel get-children)))
         (send resizable-panel set-percentages
-              (let ([p (preferences:get 'drracket:window-size-percentage)])
+              (let ([p (preferences:get 'drracket:unit-window-size-percentage)])
                 (list p (- 1 p)))))
       
       (set-label-prefix (string-constant drscheme))