diff --git a/.circleci/config.yml b/.circleci/config.yml
index f0c3edb..66a445e 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -51,6 +51,7 @@ jobs:
       - run:
           name: Publish
           command: |
+            npm run build
             if [ "$CIRCLE_BRANCH" == "master" ]; then
               npm run publish
             fi
diff --git a/src/plugin.js b/src/plugin.js
index a403b27..f2c2480 100644
--- a/src/plugin.js
+++ b/src/plugin.js
@@ -20,11 +20,7 @@ export const resolve = (value$, getKeys, getObservable, keyName = 'id') => {
         return combineLatest(
           keys.map(key =>
             getObservable(key).pipe(
-              map(value => {
-                const valueWithKey = { ...value };
-                valueWithKey[keyName] = key;
-                return valueWithKey;
-              })
+              map(value => Object.assign({ [keyName]: key }, value))
             )
           )
         );