diff --git a/tests/lib/themeManager.test.js b/tests/lib/themeManager.test.js
index d24f4937..f388fea9 100644
--- a/tests/lib/themeManager.test.js
+++ b/tests/lib/themeManager.test.js
@@ -12,7 +12,7 @@ const originalDate = Date
 let context = {}
 
 beforeAll(() => {
-  const constantDate = new Date('2017-11-27T14:33:42Z')
+  const constantDate = new Date('2017-11-27T14:33:42')
   global.Date = class extends Date {
     constructor() {
       super()