diff --git a/src/mac/carbon/toplevel.cpp b/src/mac/carbon/toplevel.cpp
index c51f6c34b2..34ab75e61c 100644
--- a/src/mac/carbon/toplevel.cpp
+++ b/src/mac/carbon/toplevel.cpp
@@ -363,12 +363,15 @@ void SetupMouseEvent( wxMouseEvent &wxevent , wxMacCarbonEvent &cEvent )
             {
                 wxevent.SetEventType( wxEVT_MOUSEWHEEL ) ;
 
-                // EventMouseWheelAxis axis = cEvent.GetParameter<EventMouseWheelAxis>(kEventParamMouseWheelAxis, typeMouseWheelAxis) ;
+                EventMouseWheelAxis axis = cEvent.GetParameter<EventMouseWheelAxis>(kEventParamMouseWheelAxis, typeMouseWheelAxis) ;
                 SInt32 delta = cEvent.GetParameter<SInt32>(kEventParamMouseWheelDelta, typeSInt32) ;
 
-                wxevent.m_wheelRotation = delta;
-                wxevent.m_wheelDelta = 1;
-                wxevent.m_linesPerAction = 1;
+                if ( axis == kEventMouseWheelAxisY )
+                {
+                    wxevent.m_wheelRotation = delta;
+                    wxevent.m_wheelDelta = 1;
+                    wxevent.m_linesPerAction = 1;
+                }
             }
             break ;
         case kEventMouseEntered :