diff --git a/klippy/extras/heaters.py b/klippy/extras/heaters.py
index c20a2e29b..079a2dc6e 100644
--- a/klippy/extras/heaters.py
+++ b/klippy/extras/heaters.py
@@ -1077,7 +1077,7 @@ def set_temperature(self, heater, temp, wait=False):
             if not mcu_name.startswith("mcu"):
                 mcu_name = "mcu " + mcu_name
             mcu_object = self.printer.lookup_object(mcu_name, None)
-            if not mcu_object.non_critical_disconnected:
+            if mcu_object is not None and not mcu_object.non_critical_disconnected:
                 heater.notify_disabled(mcu_name)
                 return
         toolhead = self.printer.lookup_object("toolhead")