diff --git a/exir/pass_base.py b/exir/pass_base.py
index 9c97921f51b..a4b5e65263c 100644
--- a/exir/pass_base.py
+++ b/exir/pass_base.py
@@ -726,7 +726,6 @@ def update(key: K, args: MutableMapping[K, PyTree], schema: ArgSchema) -> None:
         args[key] = fn(args[key], schema)
 
     for i, schema in enumerate(op._schema.arguments):
-        assert isinstance(schema, ArgSchema)
         if schema.name in kwargs:
             update(schema.name, kwargs, schema)
         elif not schema.kwarg_only and i < len(args):