diff --git a/src/onedb/onedb.rb b/src/onedb/onedb.rb
index 381215648e..6aa6b5f881 100644
--- a/src/onedb/onedb.rb
+++ b/src/onedb/onedb.rb
@@ -90,6 +90,7 @@ class OneDB
 
     def history
         @backend.history
+        return 0
     end
 
     def upgrade(max_version, ops)