diff --git a/sys/shell/commands/sc_cord_ep.c b/sys/shell/commands/sc_cord_ep.c
index f4b1152590e65..3b056b8c7fc8d 100644
--- a/sys/shell/commands/sc_cord_ep.c
+++ b/sys/shell/commands/sc_cord_ep.c
@@ -63,6 +63,10 @@ int _cord_ep_handler(int argc, char **argv)
         }
         if (argc > 3) {
             regif = argv[3];
+            if (regif[0] != '/') {
+                puts("error: registration interface must start with '/'");
+                return 1;
+            }
         }
         puts("Registering with RD now, this may take a short while...");
         if (cord_ep_register(&remote, regif) != CORD_EP_OK) {