diff --git a/isisd/isis_dynhn.c b/isisd/isis_dynhn.c
index ffb0d50..412f098 100644
--- a/isisd/isis_dynhn.c
+++ b/isisd/isis_dynhn.c
@@ -78,7 +78,7 @@
 }
 
 struct isis_dynhn *
-dynhn_find_by_id (u_char * id)
+dynhn_find_by_id (const u_char * id)
 {
   struct listnode *node = NULL;
   struct isis_dynhn *dyn = NULL;
@@ -104,7 +104,7 @@
 }
 
 void
-isis_dynhn_insert (u_char * id, struct hostname *hostname, int level)
+isis_dynhn_insert (const u_char * id, struct hostname *hostname, int level)
 {
   struct isis_dynhn *dyn;
 
@@ -135,7 +135,7 @@
 }
 
 void
-isis_dynhn_remove (u_char * id)
+isis_dynhn_remove (const u_char * id)
 {
   struct isis_dynhn *dyn;