diff --git a/src/plumpy/base/state_machine.py b/src/plumpy/base/state_machine.py
index 499612e0..853ca668 100644
--- a/src/plumpy/base/state_machine.py
+++ b/src/plumpy/base/state_machine.py
@@ -312,7 +312,7 @@ def _fire_state_event(self, hook: Hashable, state: Optional[State]) -> None:
     def on_terminated(self) -> None:
         """Called when a terminal state is entered"""
 
-    def transition_to(self, new_state: Union[State, Type[State]], **kwargs: Any) -> None:
+    def transition_to(self, new_state: State | type[State] | None, **kwargs: Any) -> None:
         """Transite to the new state.
 
         The new target state will be create lazily when the state is not yet instantiated,
@@ -322,6 +322,9 @@ def transition_to(self, new_state: Union[State, Type[State]], **kwargs: Any) ->
         """
         assert not self._transitioning, 'Cannot call transition_to when already transitioning state'
 
+        if new_state is None:
+            return None
+
         initial_state_label = self._state.LABEL if self._state is not None else None
         label = None
         try: