PyWeakref_GetObject returns None (not NULL) when the referent is gone.
diff --git a/Doc/api/concrete.tex b/Doc/api/concrete.tex
index 93a7bd2..03f77b6 100644
--- a/Doc/api/concrete.tex
+++ b/Doc/api/concrete.tex
@@ -2409,7 +2409,7 @@
\begin{cfuncdesc}{PyObject*}{PyWeakref_GetObject}{PyObject *ref}
Returns the referenced object from a weak reference, \var{ref}. If
- the referent is no longer live, returns \NULL.
+ the referent is no longer live, returns \code{None}.
\versionadded{2.2}
\end{cfuncdesc}