diff --git a/src/attr/exceptions.pyi b/src/attr/exceptions.pyi
index 8d6bd39b..736fde2e 100644
--- a/src/attr/exceptions.pyi
+++ b/src/attr/exceptions.pyi
@@ -7,6 +7,7 @@ class AttrsAttributeNotFoundError(ValueError): ...
 class NotAnAttrsClassError(ValueError): ...
 class DefaultAlreadySetError(RuntimeError): ...
 class UnannotatedAttributeError(RuntimeError): ...
+class PythonTooOldError(RuntimeError): ...
 
 class NotCallableError(TypeError):
     msg: str = ...