diff --git a/collects/mred/private/wx/cocoa/canvas.rkt b/collects/mred/private/wx/cocoa/canvas.rkt
index bf75a67ad1..e791fc55d8 100644
--- a/collects/mred/private/wx/cocoa/canvas.rkt
+++ b/collects/mred/private/wx/cocoa/canvas.rkt
@@ -561,7 +561,7 @@
                                      0.0)))]
         [(scroller)
          (if scroller
-             (->long (round (* (tell #:type _double (scroller-cocoa scroller) floatValue)
+             (->long (round (* (tell #:type _float (scroller-cocoa scroller) floatValue)
                                (scroller-range scroller))))
              0)]))