diff --git a/man2/chdir.2 b/man2/chdir.2
index cd8151234..e6650805a 100644
--- a/man2/chdir.2
+++ b/man2/chdir.2
@@ -113,8 +113,10 @@ The current working directory is left unchanged by
 The prototype for
 .BR fchdir ()
 is only available if
-.B _BSD_SOURCE
-is defined.
+.B _BSD_SOURCE 
+is defined, or
+.B _XOPEN_SOURCE
+is defined with the value 500.
 .SH "CONFORMING TO"
 SVr4, 4.4BSD, POSIX.1-2001.
 .SH "SEE ALSO"