diff --git a/telethon/events/chataction.py b/telethon/events/chataction.py
index 623c80a9..b9db44cd 100644
--- a/telethon/events/chataction.py
+++ b/telethon/events/chataction.py
@@ -293,6 +293,7 @@ class ChatAction(EventBuilder):
             if self.users or await self.get_users():
                 return self._users[0]
 
+        @property
         def input_user(self):
             """
             Input version of the ``self.user`` property.