--- a/configure.ac
+++ b/configure.ac
@@ -3946,7 +3946,7 @@
     AC_DEFINE([linux], [1], [Linux OS])
 dnl    AC_DEFINE([__i386__], [1], [Intel 386 machine])
     AC_DEFINE([_POSIX_SOURCE], [1], [POSIX source])
-    AC_DEFINE([_BSD_SOURCE], [1], [BSD source])
+    AC_DEFINE([_DEFAULT_SOURCE], [1], [DEFAULT source])
     AC_DEFINE([_GNU_SOURCE], [1], [GNU source])
 dnl    AC_DEFINE([DX_LOCALE], [1], [DX Locale])
     if test -e /etc/shadow ; then