--- a/gfx/layers/apz/src/APZCTreeManager.cpp
+++ b/gfx/layers/apz/src/APZCTreeManager.cpp
@@ -935,25 +935,19 @@ APZCTreeManager::ProcessWheelEvent(Widge
 // APZ. If this returns true, the event must not perform a synchronous
 // scroll.
 //
 // Even if this returns false, all wheel events in APZ-aware widgets must
 // be sent through APZ so they are transformed correctly for TabParent.
 static bool
 WillHandleWheelEvent(WidgetWheelEvent* aEvent)
 {
-  // Only support pixel units on OS X for now because it causes more test
-  // failures when APZ is turned on, and we want to do that on Windows very
-  // soon.
   return EventStateManager::WheelEventIsScrollAction(aEvent) &&
          (aEvent->deltaMode == nsIDOMWheelEvent::DOM_DELTA_LINE
-#ifdef XP_MACOSX
-            || aEvent->deltaMode == nsIDOMWheelEvent::DOM_DELTA_PIXEL
-#endif
-           ) &&
+            || aEvent->deltaMode == nsIDOMWheelEvent::DOM_DELTA_PIXEL) &&
          !EventStateManager::WheelEventNeedsDeltaMultipliers(aEvent);
 }
 
 nsEventStatus
 APZCTreeManager::ReceiveInputEvent(WidgetInputEvent& aEvent,
                                    ScrollableLayerGuid* aOutTargetGuid,
                                    uint64_t* aOutInputBlockId)
 {