diff --git a/cura/BuildVolume.py b/cura/BuildVolume.py
index 8cbe535ea7..64dc4faceb 100755
--- a/cura/BuildVolume.py
+++ b/cura/BuildVolume.py
@@ -848,7 +848,7 @@ class BuildVolume(SceneNode):
         """
 
         result = {}
-        skirt_brim_extruder = None #type: ExtruderStack
+        skirt_brim_extruder: ExtruderStack = None
         for extruder in used_extruders:
             if int(extruder.getProperty("extruder_nr", "value")) == int(self._global_container_stack.getProperty("skirt_brim_extruder_nr", "value")):
                 skirt_brim_extruder = extruder