diff --git a/lib/if_rmap.h b/lib/if_rmap.h
index a9355ab..540d68f 100644
--- a/lib/if_rmap.h
+++ b/lib/if_rmap.h
@@ -41,7 +41,7 @@
 void if_rmap_reset (void);
 void if_rmap_hook_add (void (*) (struct if_rmap *));
 void if_rmap_hook_delete (void (*) (struct if_rmap *));
-struct if_rmap *if_rmap_lookup (char *);
+struct if_rmap *if_rmap_lookup (const char *);
 int config_write_if_rmap (struct vty *);
 
 #endif /* _ZEBRA_IF_RMAP_H */