--- a/dom/events/EventStateManager.cpp
+++ b/dom/events/EventStateManager.cpp
@@ -1863,19 +1863,21 @@ EventStateManager::IsEventOutsideDragThr
     sPixelThresholdY =
       LookAndFeel::GetInt(LookAndFeel::eIntID_DragThresholdY, 0);
     if (!sPixelThresholdX)
       sPixelThresholdX = 5;
     if (!sPixelThresholdY)
       sPixelThresholdY = 5;
   }
 
+  auto touchEvent = aEvent->AsTouchEvent();
   LayoutDeviceIntPoint pt = aEvent->mWidget->WidgetToScreenOffset() +
-    (aEvent->AsTouchEvent() ? aEvent->AsTouchEvent()->mTouches[0]->mRefPoint
-                            : aEvent->mRefPoint);
+    ((touchEvent && !touchEvent->mTouches.IsEmpty())
+      ? aEvent->AsTouchEvent()->mTouches[0]->mRefPoint
+      : aEvent->mRefPoint);
   LayoutDeviceIntPoint distance = pt - mGestureDownPoint;
   return
     Abs(distance.x) > AssertedCast<uint32_t>(sPixelThresholdX) ||
     Abs(distance.y) > AssertedCast<uint32_t>(sPixelThresholdY);
 }
 
 //
 // GenerateDragGesture