diff --git a/manimlib/animation/transform.py b/manimlib/animation/transform.py
index 62fd87a7..012bfad9 100644
--- a/manimlib/animation/transform.py
+++ b/manimlib/animation/transform.py
@@ -70,7 +70,8 @@ class Transform(Animation):
     def finish(self) -> None:
         super().finish()
         self.mobject.unlock_data()
-        self.mobject.become(self.target_mobject)
+        if self.target_mobject is not None:
+            self.mobject.become(self.target_mobject)
 
     def create_target(self) -> Mobject:
         # Has no meaningful effect here, but may be useful