diff --git a/telethon/client/updates.py b/telethon/client/updates.py
index 1d8d0637..fb8dc26a 100644
--- a/telethon/client/updates.py
+++ b/telethon/client/updates.py
@@ -415,7 +415,7 @@ class UpdateMethods:
             if not builder.resolved:
                 await builder.resolve(self)
 
-            if not builder.filter(event):
+            if not await builder.filter(event):
                 continue
 
             try:
diff --git a/telethon/events/callbackquery.py b/telethon/events/callbackquery.py
index cb879682..fc759ba6 100644
--- a/telethon/events/callbackquery.py
+++ b/telethon/events/callbackquery.py
@@ -74,7 +74,7 @@ class CallbackQuery(EventBuilder):
             peer = types.PeerChannel(-pid) if pid < 0 else types.PeerUser(pid)
             return cls.Event(update, peer, mid)
 
-    def filter(self, event):
+    async def filter(self, event):
         # We can't call super().filter(...) because it ignores chat_instance
         if self._no_check:
             return event
@@ -95,7 +95,7 @@ class CallbackQuery(EventBuilder):
             elif event.query.data != self.match:
                 return
 
-        if not self.func or self.func(event):
+        if await self._check_func(event):
             return event
 
     class Event(EventCommon, SenderGetter):
@@ -110,7 +110,7 @@ class CallbackQuery(EventBuilder):
                 The object returned by the ``data=`` parameter
                 when creating the event builder, if any. Similar
                 to ``pattern_match`` for the new message event.
-            
+
             pattern_match (`obj`, optional):
                 Alias for ``data_match``.
         """
diff --git a/telethon/events/common.py b/telethon/events/common.py
index 42586608..e175102d 100644
--- a/telethon/events/common.py
+++ b/telethon/events/common.py
@@ -2,6 +2,7 @@ import abc
 import asyncio
 import itertools
 import warnings
+import inspect
 
 from .. import utils
 from ..tl import TLObject, types, functions
@@ -103,7 +104,7 @@ class EventBuilder(abc.ABC):
     async def _resolve(self, client):
         self.chats = await _into_id_set(client, self.chats)
 
-    def filter(self, event):
+    async def filter(self, event):
         """
         If the ID of ``event._chat_peer`` isn't in the chats set (or it is
         but the set is a blacklist) returns `None`, otherwise the event.
@@ -121,9 +122,15 @@ class EventBuilder(abc.ABC):
                 # If it doesn't match but it's a whitelist ignore.
                 return None
 
-        if not self.func or self.func(event):
+        if await self._check_func(event):
             return event
 
+    async def _check_func(self, event):
+        if not self.func:
+            return True
+        r = self.func(event)
+        return await r if inspect.isawaitable(r) else r
+
 
 class EventCommon(ChatGetter, abc.ABC):
     """
diff --git a/telethon/events/inlinequery.py b/telethon/events/inlinequery.py
index 73044700..0fdc1100 100644
--- a/telethon/events/inlinequery.py
+++ b/telethon/events/inlinequery.py
@@ -50,14 +50,14 @@ class InlineQuery(EventBuilder):
         if isinstance(update, types.UpdateBotInlineQuery):
             return cls.Event(update)
 
-    def filter(self, event):
+    async def filter(self, event):
         if self.pattern:
             match = self.pattern(event.text)
             if not match:
                 return
             event.pattern_match = match
 
-        return super().filter(event)
+        return await super().filter(event)
 
     class Event(EventCommon, SenderGetter):
         """
@@ -156,9 +156,9 @@ class InlineQuery(EventBuilder):
 
                 gallery (`bool`, optional):
                     Whether the results should show as a gallery (grid) or not.
-                
+
                 next_offset (`str`, optional):
-                    The offset the client will send when the user scrolls the 
+                    The offset the client will send when the user scrolls the
                     results and it repeats the request.
 
                 private (`bool`, optional):
diff --git a/telethon/events/messageread.py b/telethon/events/messageread.py
index 5dfec30f..e2b90d2c 100644
--- a/telethon/events/messageread.py
+++ b/telethon/events/messageread.py
@@ -39,11 +39,11 @@ class MessageRead(EventBuilder):
                              message_ids=update.messages,
                              contents=True)
 
-    def filter(self, event):
+    async def filter(self, event):
         if self.inbox == event.outbox:
             return
 
-        return super().filter(event)
+        return await super().filter(event)
 
     class Event(EventCommon):
         """
diff --git a/telethon/events/newmessage.py b/telethon/events/newmessage.py
index 3034879c..9e948e07 100644
--- a/telethon/events/newmessage.py
+++ b/telethon/events/newmessage.py
@@ -129,7 +129,7 @@ class NewMessage(EventBuilder):
 
         return event
 
-    def filter(self, event):
+    async def filter(self, event):
         if self._no_check:
             return event
 
@@ -151,7 +151,7 @@ class NewMessage(EventBuilder):
                 return
             event.pattern_match = match
 
-        return super().filter(event)
+        return await super().filter(event)
 
     class Event(EventCommon):
         """
diff --git a/telethon/events/raw.py b/telethon/events/raw.py
index f0a4cd9d..a1bdcb29 100644
--- a/telethon/events/raw.py
+++ b/telethon/events/raw.py
@@ -35,7 +35,7 @@ class Raw(EventBuilder):
     def build(cls, update, others=None, self_id=None):
         return update
 
-    def filter(self, event):
+    async def filter(self, event):
         if ((not self.types or isinstance(event, self.types))
-                and (not self.func or self.func(event))):
+                and await self._check_func(event)):
             return event