diff --git a/ChangeLog b/ChangeLog
index 432526f64..8282afa1a 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2006-04-30  David Ayers  <d.ayers@inode.at>
+
+	* Source/NSString: Define _GNU_SOURCE to make protoype of fwprintf
+	visible.
+
 2006-04-28  Richard Frith-Macdonald <rfm@gnu.org>
 
 	* Source/NSKeyedUnarchiver.m: Fix decoding of NSNull objects.
diff --git a/Source/NSString.m b/Source/NSString.m
index 430f8dc19..87fd740f8 100644
--- a/Source/NSString.m
+++ b/Source/NSString.m
@@ -43,6 +43,11 @@
    Limited choice of default encodings.
 */
 
+/* Needed for visiblity of fwprintf prototype.  */
+#ifndef _GNU_SOURCE
+#define _GNU_SOURCE
+#endif
+
 #include "config.h"
 #include <stdio.h>
 #include <string.h>