diff --git a/lib/vty.h b/lib/vty.h
index 4d6048c..f31f4b5 100644
--- a/lib/vty.h
+++ b/lib/vty.h
@@ -217,6 +217,14 @@
     }                                                                         \
 } while (0)
 
+#define VTY_WARN_EXPERIMENTAL()                                               \
+do {                                                                          \
+  vty_out (vty, "%% WARNING: this command is experimental. Both its name and" \
+                " parameters may%s%% change in a future version of Quagga,"   \
+                " possibly breaking your configuration!%s",                   \
+                VTY_NEWLINE, VTY_NEWLINE);                                    \
+} while (0)
+
 /* Exported variables */
 extern char integrate_default[];