diff --git a/stdlib/2/types.pyi b/stdlib/2/types.pyi
index 15c8dd9c0..0f195ba6a 100644
--- a/stdlib/2/types.pyi
+++ b/stdlib/2/types.pyi
@@ -103,7 +103,7 @@ class ModuleType:
     __name__ = ...  # type: str
     __package__ = ...  # type: Optional[str]
     __path__ = ...  # type: Optional[Iterable[str]]
-    def __init__(self, name: str, doc: str) -> None: ...
+    def __init__(self, name: str, doc: Optional[str] = ...) -> None: ...
 FileType = file
 XRangeType = xrange
 
diff --git a/stdlib/3/_importlib_modulespec.pyi b/stdlib/3/_importlib_modulespec.pyi
index 1acd9f124..6b80ab68c 100644
--- a/stdlib/3/_importlib_modulespec.pyi
+++ b/stdlib/3/_importlib_modulespec.pyi
@@ -30,7 +30,7 @@ class ModuleType:
         __loader__ = ...  # type: Optional[Loader]
         __package__ = ...  # type: Optional[str]
         __spec__ = ...  # type: Optional[ModuleSpec]
-    def __init__(self, name: str, doc: str) -> None: ...
+    def __init__(self, name: str, doc: Optional[str] = ...) -> None: ...
 
 class Loader(metaclass=ABCMeta):
     def load_module(self, fullname: str) -> ModuleType: ...