diff --git a/commands2/button/trigger.py b/commands2/button/trigger.py
index cdfe207..0534f8a 100644
--- a/commands2/button/trigger.py
+++ b/commands2/button/trigger.py
@@ -84,7 +84,7 @@ def init_condition(condition: Callable[[], bool]):
 """
         )
 
-    def _add_binding(self, body: Callable[bool, bool, NoneType]) -> None:
+    def _add_binding(self, body: Callable[[bool, bool], None]) -> None:
         """
         Adds a binding to the EventLoop.