diff --git hwnd_message_handler.cc hwnd_message_handler.cc
index 035df76..d1517b4 100644
--- hwnd_message_handler.cc
+++ hwnd_message_handler.cc
@@ -2364,8 +2364,12 @@ LRESULT HWNDMessageHandler::HandleMouseEventInternal(UINT message,
     active_mouse_tracking_flags_ = 0;
   } else if (event.type() == ui::ET_MOUSEWHEEL) {
     // Reroute the mouse wheel to the window under the pointer if applicable.
-    return (ui::RerouteMouseWheel(hwnd(), w_param, l_param) ||
-            delegate_->HandleMouseEvent(ui::MouseWheelEvent(msg))) ? 0 : 1;
+    if (ui::RerouteMouseWheel(hwnd(), w_param, l_param) ||
+        delegate_->HandleMouseEvent(ui::MouseWheelEvent(msg))) {
+      SetMsgHandled(TRUE);
+      return 0;
+    }
+    return 1;
   }
 
   // There are cases where the code handling the message destroys the window,