diff --git a/electrum/gui/qt/channel_details.py b/electrum/gui/qt/channel_details.py
index 6a783b556..e6d624cef 100644
--- a/electrum/gui/qt/channel_details.py
+++ b/electrum/gui/qt/channel_details.py
@@ -224,3 +224,7 @@ class ChannelDetailsDialog(QtWidgets.QDialog, MessageBoxMixin, QtEventListener):
         vbox.addLayout(Buttons(CloseButton(self)))
         # initialize sent/received fields
         self.update()
+
+    def closeEvent(self, event):
+        self.unregister_callbacks()
+        event.accept()
diff --git a/electrum/gui/qt/settings_dialog.py b/electrum/gui/qt/settings_dialog.py
index e2225ddb0..a88483779 100644
--- a/electrum/gui/qt/settings_dialog.py
+++ b/electrum/gui/qt/settings_dialog.py
@@ -580,3 +580,11 @@ class SettingsDialog(QDialog, QtEventListener):
         self.config.set_key('alias', alias, True)
         if alias:
             self.wallet.contacts.fetch_openalias(self.config)
+
+    def closeEvent(self, event):
+        self.unregister_callbacks()
+        try:
+            self.app.alias_received_signal.disconnect(self.set_alias_color)
+        except TypeError:
+            pass  # 'method' object is not connected
+        event.accept()