diff --git a/Tk/Widget.pm b/Tk/Widget.pm
index 62cb5c44..467835e5 100644
--- a/Tk/Widget.pm
+++ b/Tk/Widget.pm
@@ -1106,9 +1106,11 @@ sub MouseWheelBind
  # events on other platforms.
 
  $mw->Tk::bind($class, '<MouseWheel>',
-	       [ sub { $_[0]->yview('scroll',-($_[1]/120)*3,'units') }, Tk::Ev("D")]);
+    $mw->windowingsystem eq 'aqua'
+	    ? [ sub { $_[0]->yview('scroll',-($_[1]),'units') }, Tk::Ev("D")]
+	    : [ sub { $_[0]->yview('scroll',-($_[1]/120)*3,'units') }, Tk::Ev("D")]);
 
- if ($Tk::platform eq 'unix')
+ if ($mw->windowingsystem eq 'x11')
   {
    # Support for mousewheels on Linux/Unix commonly comes through mapping
    # the wheel to the extended buttons.  If you have a mousewheel, find