diff --git a/src/legacy/ui/public/timefilter/setup_router.test.js b/src/legacy/ui/public/timefilter/setup_router.test.js
new file mode 100644
index 000000000000..4bc797e5eff0
--- /dev/null
+++ b/src/legacy/ui/public/timefilter/setup_router.test.js
@@ -0,0 +1,53 @@
+/*
+ * Licensed to Elasticsearch B.V. under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch B.V. licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+import { registerTimefilterWithGlobalState } from './setup_router';
+
+jest.mock('ui/utils/subscribe_with_scope', () => ({
+  subscribeWithScope: jest.fn()
+}));
+
+describe('registerTimefilterWithGlobalState()', () => {
+  it('should always use iso8601 strings', async () => {
+    const setTime = jest.fn();
+    const timefilter = {
+      setTime,
+      setRefreshInterval: jest.fn(),
+      getRefreshIntervalUpdate$: jest.fn(),
+      getTimeUpdate$: jest.fn()
+    };
+
+    const globalState = {
+      time: {
+        from: '2017-09-07T20:12:04.011Z',
+        to: '2017-09-07T20:18:55.733Z',
+      },
+      on: (eventName, callback) => {
+        callback();
+      }
+    };
+
+    registerTimefilterWithGlobalState(
+      timefilter,
+      globalState
+    );
+
+    expect(setTime.mock.calls.length).toBe(2);
+    expect(setTime.mock.calls[1][0]).toEqual(globalState.time);
+  });
+});
diff --git a/src/legacy/ui/public/timefilter/setup_router.ts b/src/legacy/ui/public/timefilter/setup_router.ts
index 3c81fde89149..ffc8a1fca6c6 100644
--- a/src/legacy/ui/public/timefilter/setup_router.ts
+++ b/src/legacy/ui/public/timefilter/setup_router.ts
@@ -30,7 +30,7 @@ import { TimefilterContract } from '../../../core_plugins/data/public/timefilter
 // and listener can be registered without angular.
 function convertISO8601(stringTime: string): string {
   const obj = moment(stringTime, 'YYYY-MM-DDTHH:mm:ss.SSSZ', true);
-  return obj.isValid() ? obj.toString() : stringTime;
+  return obj.isValid() ? obj.toISOString() : stringTime;
 }
 
 export function getTimefilterConfig() {