diff --git a/stdlib/unittest/case.pyi b/stdlib/unittest/case.pyi
index a602196e73c6..7a02bdfe76b4 100644
--- a/stdlib/unittest/case.pyi
+++ b/stdlib/unittest/case.pyi
@@ -54,7 +54,7 @@ def skipIf(condition: object, reason: str) -> Callable[[_FT], _FT]: ...
 def skipUnless(condition: object, reason: str) -> Callable[[_FT], _FT]: ...
 
 class SkipTest(Exception):
-    def __init__(self, reason: str) -> None: ...
+    def __init__(self, reason: str, /) -> None: ...
 
 @type_check_only
 class _SupportsAbsAndDunderGE(SupportsDunderGE[Any], SupportsAbs[Any], Protocol): ...