diff --git a/third_party/3/typed_ast/ast27.pyi b/third_party/3/typed_ast/ast27.pyi
index 40b44da83..8e88972a9 100644
--- a/third_party/3/typed_ast/ast27.pyi
+++ b/third_party/3/typed_ast/ast27.pyi
@@ -347,6 +347,7 @@ class arguments(AST):
     vararg = ...  # type: Optional[identifier]
     kwarg = ...  # type: Optional[identifier]
     defaults = ...  # type: typing.List[expr]
+    type_comments = ...  # type: typing.List[str]
 
 class keyword(AST):
     arg = ...  # type: identifier