diff --git a/telethon/client/updates.py b/telethon/client/updates.py
index 7019b465..10eb8a77 100644
--- a/telethon/client/updates.py
+++ b/telethon/client/updates.py
@@ -426,7 +426,8 @@ class UpdateMethods:
                 await builder.resolve(self)
 
             filter = builder.filter(event)
-            filter = (await filter) if inspect.isawaitable(filter) else filter
+            if inspect.isawaitable(filter):
+                filter = await filter
             if not filter:
                 continue
 
diff --git a/telethon/events/common.py b/telethon/events/common.py
index fd3315f5..f2ca12a7 100644
--- a/telethon/events/common.py
+++ b/telethon/events/common.py
@@ -125,6 +125,7 @@ class EventBuilder(abc.ABC):
         if not self.func:
             return True
 
+        # Return the result of func directly as it may need to be awaited
         return self.func(event)