diff --git a/b_asic/GUI/arrow.py b/b_asic/GUI/arrow.py
index c66b5859a69f045b4c28b33f70426d43117efdf4..aea8fec3b488d7fbfe49766f3a23b3fa2346a920 100644
--- a/b_asic/GUI/arrow.py
+++ b/b_asic/GUI/arrow.py
@@ -31,7 +31,6 @@ class Arrow(QGraphicsLineItem):
         self.signal.remove_source()
         self._window.scene.removeItem(self)
         self._window.signalList.remove(self)
-        del self._window.signalPortDict[self]
 
     def moveLine(self):
         self.setPen(QPen(Qt.black, 3))