diff --git a/pytec/tec_qt.py b/pytec/tec_qt.py
index 4c45c19..0cf202d 100644
--- a/pytec/tec_qt.py
+++ b/pytec/tec_qt.py
@@ -439,7 +439,7 @@ class MainWindow(QtWidgets.QMainWindow):
         assert self.thermostat.connected()
 
         await self.thermostat.set_ipv4(ipv4_settings)
-        await self.thermostat._client.end_session()
+        await self.thermostat.end_session()
         await self._on_connection_changed(False)