diff --git a/jest.e2e.config.js b/jest.e2e.config.js
index 16df068a353..05553dd26e9 100644
--- a/jest.e2e.config.js
+++ b/jest.e2e.config.js
@@ -1,6 +1,5 @@
 const conf = require('./jest.config');
 
-module.exports = {
-  ...conf,
+module.exports = Object.assign(conf, {
   testMatch: ['<rootDir>/test/e2e/**/*.spec.ts']
-};
+});
diff --git a/jest.unit.config.js b/jest.unit.config.js
index 19cd0998411..cfc560909f7 100644
--- a/jest.unit.config.js
+++ b/jest.unit.config.js
@@ -1,8 +1,7 @@
 const conf = require('./jest.config');
 
-module.exports = {
-  ...conf,
+module.exports = Object.assign(conf, {
   testMatch: ['<rootDir>/test/unit/**/*.spec.ts'],
   coverageDirectory: 'coverage',
   coveragePathIgnorePatterns: ['<rootDir>/lib/', '<rootDir>/test/', '<rootDir>/node_modules/']
-};
+});