diff --git a/src/Generator.php b/src/Generator.php
index f5d854e..200f0c3 100644
--- a/src/Generator.php
+++ b/src/Generator.php
@@ -357,7 +357,7 @@ private function getUMDModule($body)
 (function (global, factory) {
     typeof exports === 'object' && typeof module !== 'undefined' ? module.exports = factory() :
         typeof define === 'function' && define.amd ? define(factory) :
-            (global.vuei18nLocales = factory());
+            typeof global.vuei18nLocales === 'undefined' ? global.vuei18nLocales = factory() : Object.keys(factory()).forEach(function (key) {global.vuei18nLocales[key] = factory()[key]});
 }(this, (function () { 'use strict';
     return {$body}
 })));
diff --git a/tests/GenerateTest.php b/tests/GenerateTest.php
index 85eac85..1f218dc 100644
--- a/tests/GenerateTest.php
+++ b/tests/GenerateTest.php
@@ -211,7 +211,7 @@ function testBasicWithUMDFormat()
             '(function (global, factory) {' . PHP_EOL
             . '    typeof exports === \'object\' && typeof module !== \'undefined\' ? module.exports = factory() :' . PHP_EOL
             . '        typeof define === \'function\' && define.amd ? define(factory) :' . PHP_EOL
-            . '            (global.vuei18nLocales = factory());' . PHP_EOL
+            . '            typeof global.vuei18nLocales === \'undefined\' ? global.vuei18nLocales = factory() : Object.keys(factory()).forEach(function (key) {global.vuei18nLocales[key] = factory()[key]});' . PHP_EOL
             . '}(this, (function () { \'use strict\';' . PHP_EOL
             . '    return {' . PHP_EOL
             . '    "en": {' . PHP_EOL