diff --git a/telethon/utils.py b/telethon/utils.py
index a033d3ef..f7b830e7 100644
--- a/telethon/utils.py
+++ b/telethon/utils.py
@@ -583,6 +583,9 @@ def _get_entity_pair(entity_id, entities, cache,
     """
     Returns ``(entity, input_entity)`` for the given entity ID.
     """
+    if not entity_id:
+        return None, None
+
     entity = entities.get(entity_id)
     try:
         input_entity = cache.get(resolve_id(entity_id)[0])._as_input_peer()