diff --git a/pyqtgraph/widgets/GraphicsView.py b/pyqtgraph/widgets/GraphicsView.py
index e1a7327e..b81eab9d 100644
--- a/pyqtgraph/widgets/GraphicsView.py
+++ b/pyqtgraph/widgets/GraphicsView.py
@@ -362,7 +362,7 @@ class GraphicsView(QtGui.QGraphicsView):
     def mouseMoveEvent(self, ev):
         if self.lastMousePos is None:
             self.lastMousePos = Point(ev.pos())
-        delta = Point(ev.pos() - self.lastMousePos)
+        delta = Point(ev.pos() - QtCore.QPoint(*self.lastMousePos))
         self.lastMousePos = Point(ev.pos())
 
         QtGui.QGraphicsView.mouseMoveEvent(self, ev)