diff --git a/zlib/ChangeLog.gcj b/zlib/ChangeLog.gcj
index 5569030bb7dd449cbe12af3f51b3f8ca12702e53..39e5a0d118c9b4afd5809971438544e693344ef4 100644
--- a/zlib/ChangeLog.gcj
+++ b/zlib/ChangeLog.gcj
@@ -1,3 +1,7 @@
+2004-11-22  Eric Botcazou  <ebotcazou@libertysurf.fr>
+
+	* zconf.h: Define NO_vsnprintf on Solaris 2.5.1.
+
 2004-10-11  Tom Tromey  <tromey@redhat.com>
 
 	PR libgcj/14856:
diff --git a/zlib/zconf.h b/zlib/zconf.h
index 831285e8efb0c27179a257c4c0b7ca0216bc1a4d..96dbc205c919f3e28d41a7a9cbb4748951217b85 100644
--- a/zlib/zconf.h
+++ b/zlib/zconf.h
@@ -320,4 +320,12 @@ typedef uLong FAR uLongf;
 #   pragma map(inflate_copyright,"INCOPY")
 #endif
 
+/* Solaris 2.5.1 doesn't have vsnprintf */
+#if defined(__sun) && defined(__svr4__)
+#include <sys/feature_tests.h>
+#if _XOPEN_VERSION < 3
+#define NO_vsnprintf
+#endif
+#endif
+
 #endif /* ZCONF_H */