diff --git a/lib/vty.h b/lib/vty.h
index 1798585..4d6048c 100644
--- a/lib/vty.h
+++ b/lib/vty.h
@@ -242,6 +242,6 @@
 
 /* Send a fixed-size message to all vty terminal monitors; this should be
    an async-signal-safe function. */
-extern void vty_log_fixed (const char *buf, size_t len);
+extern void vty_log_fixed (char *buf, size_t len);
 
 #endif /* _ZEBRA_VTY_H */