diff --git a/blenderproc/python/utility/Initializer.py b/blenderproc/python/utility/Initializer.py
index 8e46f505f..544a3eba9 100644
--- a/blenderproc/python/utility/Initializer.py
+++ b/blenderproc/python/utility/Initializer.py
@@ -162,5 +162,5 @@ def remove_all_data(remove_camera: bool = True):
     @staticmethod
     def remove_custom_properties():
         """ Remove all custom properties registered at global entities like the scene. """
-        for key in bpy.context.scene.keys():
+        for key in list(bpy.context.scene.keys()):
             del bpy.context.scene[key]