diff --git a/src/sync-state.proto b/src/sync-state.proto
index 26095e1..410726b 100644
--- a/src/sync-state.proto
+++ b/src/sync-state.proto
@@ -11,6 +11,7 @@
 
   optional uint64 seq = 3;
   optional bytes locator = 4;
+  optional uint64 old_seq = 5;
 }
 
 message SyncStateMsg