diff --git a/stdlib/2and3/ctypes/__init__.pyi b/stdlib/2and3/ctypes/__init__.pyi
index e4cd6b48f..2c7653f5f 100644
--- a/stdlib/2and3/ctypes/__init__.pyi
+++ b/stdlib/2and3/ctypes/__init__.pyi
@@ -228,7 +228,7 @@ class c_wchar_p(_PointerLike, _SimpleCData[Optional[Text]]):
     def __init__(self, value: Optional[_UnionT[int, Text]] = ...) -> None: ...
 
 class c_bool(_SimpleCData[bool]):
-    def __init__(self, value: bool) -> None: ...
+    def __init__(self, value: bool = ...) -> None: ...
 
 if sys.platform == 'win32':
     class HRESULT(_SimpleCData[int]): ...  # TODO undocumented