diff --git a/Objects/unicodeobject.c b/Objects/unicodeobject.c
index 603c507..524859c 100644
--- a/Objects/unicodeobject.c
+++ b/Objects/unicodeobject.c
@@ -7747,8 +7747,8 @@
 PyDoc_STRVAR(zfill__doc__,
 "S.zfill(width) -> unicode\n\
 \n\
-Pad a numeric string x with zeros on the left, to fill a field\n\
-of the specified width. The string x is never truncated.");
+Pad a numeric string S with zeros on the left, to fill a field\n\
+of the specified width. The string S is never truncated.");
 
 static PyObject *
 unicode_zfill(PyUnicodeObject *self, PyObject *args)