diff --git a/libio/ChangeLog b/libio/ChangeLog
index bb3722cc4e514d475a50b67de2107571c60de0dc..e835328d8e79d90aef45ecdce70b79174a465f31 100644
--- a/libio/ChangeLog
+++ b/libio/ChangeLog
@@ -1,3 +1,7 @@
+Sat Jan 30 08:07:56 1999  Mumit Khan  <khan@xraylith.wisc.edu>
+
+	* stdiostream.cc (_POSIX_SOURCE): Define. 
+
 1998-11-26  Manfred Hollstein  <manfred@s-direktnet.de>
 
 	* configure.in (compiler_name): Add check to detect if this
diff --git a/libio/stdiostream.cc b/libio/stdiostream.cc
index bc9bef08ab6736af7fb3a2bc1da34c1633c5d146..7fb671402e8cc1de977e527fc8302910ff471f95 100644
--- a/libio/stdiostream.cc
+++ b/libio/stdiostream.cc
@@ -1,5 +1,5 @@
 /* This is part of libio/iostream, providing -*- C++ -*- input/output.
-Copyright (C) 1993 Free Software Foundation
+Copyright (C) 1993, 1999 Free Software Foundation
 
 This file is part of the GNU IO Library.  This library is free
 software; you can redistribute it and/or modify it under the
@@ -28,6 +28,9 @@ the executable file might be covered by the GNU General Public License. */
 #pragma implementation
 #endif
 
+#ifndef _POSIX_SOURCE
+# define _POSIX_SOURCE
+#endif
 #include <stdiostream.h>
 #include "libioP.h"