diff --git a/Doc/c-api/long.rst b/Doc/c-api/long.rst
--- a/Doc/c-api/long.rst
+++ b/Doc/c-api/long.rst
@@ -78,25 +78,27 @@ All integers are implemented as "long" i
Return a new :c:type:`PyLongObject` object from the integer part of *v*, or
*NULL* on failure.
.. c:function:: PyObject* PyLong_FromString(char *str, char **pend, int base)
Return a new :c:type:`PyLongObject` based on the string value in *str*, which
- is interpreted according to the radix in *base*. If *pend* is non-*NULL*,
- *\*pend* will point to the first character in *str* which follows the
- representation of the number. If *base* is ``0``, the radix will be
- determined based on the leading characters of *str*: if *str* starts with
- ``'0x'`` or ``'0X'``, radix 16 will be used; if *str* starts with ``'0o'`` or
- ``'0O'``, radix 8 will be used; if *str* starts with ``'0b'`` or ``'0B'``,
- radix 2 will be used; otherwise radix 10 will be used. If *base* is not
- ``0``, it must be between ``2`` and ``36``, inclusive. Leading spaces are
- ignored. If there are no digits, :exc:`ValueError` will be raised.
+ is interpreted according to the radix in *base*. If *base* is ``0``, the
+ radix will be determined based on the leading characters of *str*: if *str*
+ starts with ``'0x'`` or ``'0X'``, radix 16 will be used; if *str* starts with
+ ``'0o'`` or ``'0O'``, radix 8 will be used; if *str* starts with ``'0b'`` or
+ ``'0B'``, radix 2 will be used; otherwise radix 10 will be used. If *base*
+ is not ``0``, it must be between ``2`` and ``36``, inclusive.
+
+ Leading spaces are ignored, and the representation of the number must be
+ terminted by a null byte. If *pend* is non-*NULL*, then *\*pend* will
+ point to the location of the terminating null byte. If there are no
+ digits, :exc:`ValueError` will be raised.
.. c:function:: PyObject* PyLong_FromUnicode(Py_UNICODE *u, Py_ssize_t length, int base)
Convert a sequence of Unicode digits to a Python integer value. The Unicode
string is first encoded to a byte string using :c:func:`PyUnicode_EncodeDecimal`
and then converted using :c:func:`PyLong_FromString`.