diff --git a/config.pbtxt b/config.pbtxt
index 2497e4a..6a6157d 100644
--- a/config.pbtxt
+++ b/config.pbtxt
@@ -7,6 +7,11 @@ input [
     name: "new"
     data_type: TYPE_STRING
     dims: [ -1 ]
+  },
+  {
+    name: "old"
+    data_type: TYPE_STRING
+    dims: [ -1 ]
   }
 ]