diff --git a/update_metadata.proto b/update_metadata.proto
index 28ed0c6..6c2b888 100644
--- a/update_metadata.proto
+++ b/update_metadata.proto
@@ -168,4 +168,6 @@
   optional ImageInfo old_image_info = 10;
 
   optional ImageInfo new_image_info = 11;
+
+  optional uint32 minor_version = 12 [default = 0];
 }