diff --git a/cura/Machines/QualityGroup.py b/cura/Machines/QualityGroup.py
index 6067f04038..6945162401 100644
--- a/cura/Machines/QualityGroup.py
+++ b/cura/Machines/QualityGroup.py
@@ -38,8 +38,7 @@ class QualityGroup(QObject):
         for node in [self.node_for_global] + list(self.nodes_for_extruders.values()):
             if node is None:
                 continue
-            for key in node.getContainer().getAllKeys():
-                result.add(key)
+            result.update(node.getContainer().getAllKeys())
         return result
 
     def getAllNodes(self) -> List["QualityGroup"]: