diff --git a/src/option.c b/src/option.c
index 44bd522..012b14a 100644
--- a/src/option.c
+++ b/src/option.c
@@ -5046,7 +5046,7 @@ err:
 	    new->target = target;
 	    new->ttl = ttl;
 
-	    for (arg += arglen+1; *arg && isspace((unsigned char)*arg); arg++);
+	    for (arg += arglen+1; arg != last && (!*arg || isspace((unsigned char)*arg)); arg++);
 	  }
       
 	break;