diff --git a/man3/bindresvport.3 b/man3/bindresvport.3
index d2e73a497..c3f9db5d4 100644
--- a/man3/bindresvport.3
+++ b/man3/bindresvport.3
@@ -89,6 +89,18 @@ is not NULL and
 .I sin->sin_family
 is not
 .BR AF_INET .
+.SH ATTRIBUTES
+.SS Multithreading (see pthreads(7))
+Before glibc 2.17, the
+.BR bindresvport ()
+function uses a static variable that is not protected,
+so it is not thread-safe.
+
+Since glibc 2.17,
+.\" commit f6da27e53695ad1cc0e2a9490358decbbfdff5e5
+the
+.BR bindresvport ()
+function uses a lock to protect static variable, so it is thread-safe.
 .SH CONFORMING TO
 Not in POSIX.1-2001.
 Present on the BSDs, Solaris, and many other systems.