diff --git a/lib/prefix.h b/lib/prefix.h
index a517d79..4a31750 100644
--- a/lib/prefix.h
+++ b/lib/prefix.h
@@ -173,6 +173,7 @@
 extern int str2family(const char *);
 extern int afi2family (afi_t);
 extern afi_t family2afi (int);
+extern const char *safi2str(safi_t safi);
 
 /* Check bit of the prefix. */
 extern unsigned int prefix_bit (const u_char *prefix, const u_char prefixlen);