diff --git a/src/iodine.c b/src/iodine.c
index a5ee9ca..dafd4a9 100644
--- a/src/iodine.c
+++ b/src/iodine.c
@@ -1104,7 +1104,12 @@ main(int argc, char **argv)
 		/* NOTREACHED */
 	}
 
-	set_nameserver(nameserv_addr);
+	if (nameserv_addr) {
+		set_nameserver(nameserv_addr);
+	} else {
+		usage();
+		/* NOTREACHED */
+	}	
 
 	if(strlen(topdomain) <= 128) {
 		if(check_topdomain(topdomain)) {