diff --git a/lib/ofac/update.js b/lib/ofac/update.js
index 11fe480d..8630cdf6 100644
--- a/lib/ofac/update.js
+++ b/lib/ofac/update.js
@@ -137,7 +137,7 @@ function update () {
       const promiseNewEtags = Promise.resolve(ofacSources || [])
         .then(sources => Promise.all(_.map(promiseGetEtag, sources))
           .then(etags => _.map(
-            ([source, etag]) => ({...source, etag}),
+            ([source, etag]) => _.set('etag', etag,  source),
             _.zip(sources, etags)
           ))
         )