diff --git a/src/build123d/topology.py b/src/build123d/topology.py
index 1ce4d8a2..50f5e4ae 100644
--- a/src/build123d/topology.py
+++ b/src/build123d/topology.py
@@ -2312,6 +2312,9 @@ def __deepcopy__(self, memo) -> Self:
         memo[id(self.wrapped)] = downcast(BRepBuilderAPI_Copy(self.wrapped).Shape())
         for key, value in self.__dict__.items():
             setattr(result, key, copy.deepcopy(value, memo))
+            if key == "joints":
+                for joint in result.joints.values():
+                    joint.parent = result
         return result
 
     def __copy__(self) -> Self: