diff --git a/Python/bltinmodule.c b/Python/bltinmodule.c
index 90a6b9f..33f9690 100644
--- a/Python/bltinmodule.c
+++ b/Python/bltinmodule.c
@@ -261,7 +261,7 @@
 }
 
 PyDoc_STRVAR(build_class_doc,
-"__build_class__(func, name, *bases, metaclass=None, **kwds) -> class\n\
+"__build_class__(func, name, /, *bases, [metaclass], **kwds) -> class\n\
 \n\
 Internal helper function used by the class statement.");