diff --git a/StateMachine/StateMachine.h b/StateMachine/StateMachine.h
index a0d0570..0a589a0 100644
--- a/StateMachine/StateMachine.h
+++ b/StateMachine/StateMachine.h
@@ -18,7 +18,7 @@ class StateMachine :public Graph<StateType, Operation>
 		for (auto&& [new_state, op] : paths)
 			if (op == operation)
 			{
-				if (callback_map[new_state](derive, state, new_state))
+				if (!callback_map.contains(new_state) || callback_map[new_state](derive, state, new_state))
 				{
 					state = new_state;
 					return true;