Markup fix
diff --git a/Doc/c-api/number.rst b/Doc/c-api/number.rst
index 3602287..b1458b3 100644
--- a/Doc/c-api/number.rst
+++ b/Doc/c-api/number.rst
@@ -285,7 +285,7 @@
 .. cfunction:: PyObject* PyNumber_Index(PyObject *o)
 
    Returns the *o* converted to a Python int or long on success or *NULL* with a
-   TypeError exception raised on failure.
+   :exc:`TypeError` exception raised on failure.
 
    .. versionadded:: 2.5