diff --git a/cura/Arranging/ShapeArray.py b/cura/Arranging/ShapeArray.py
index 5607c03663..45454f6239 100644
--- a/cura/Arranging/ShapeArray.py
+++ b/cura/Arranging/ShapeArray.py
@@ -74,7 +74,7 @@ class ShapeArray:
         # If the child-nodes are included, adjust convex hulls as well:
         if include_children:
             children = node.getAllChildren()
-            if not children is None:
+            if children is not None:
                 for child in children:
                     # 'Inefficient' combination of convex hulls through known code rather than mess it up:
                     child_hull = child.callDecoration("getConvexHull")
@@ -159,4 +159,4 @@ class ShapeArray:
 
         max_col_idx = (idxs[0] - p1[0]) / (p2[0] - p1[0]) * (p2[1] - p1[1]) + p1[1]
         sign = numpy.sign(p2[0] - p1[0])
-        return idxs[1] * sign <= max_col_idx * sign
\ No newline at end of file
+        return idxs[1] * sign <= max_col_idx * sign