diff --git a/assets/static/watchdog.test.js b/assets/static/watchdog.test.js
index 13b1e0f84..b32f2f5cd 100644
--- a/assets/static/watchdog.test.js
+++ b/assets/static/watchdog.test.js
@@ -1,19 +1,19 @@
+window.jQuery = require("jquery");
 const moment = require("moment");
 
+jest.useFakeTimers();
+
 test("watchdog init()", () => {
-    window.jQuery = require("jquery");
     const watchdog = require("./watchdog");
     watchdog.init(1, 1);
 });
 
 test("watchdog getLastUpdate() without pong", () => {
-    window.jQuery = require("jquery");
     const watchdog = require("./watchdog");
     expect(watchdog.getLastUpdate()).toBe(0);
 });
 
 test("watchdog getLastUpdate() with pong", () => {
-    window.jQuery = require("jquery");
     const watchdog = require("./watchdog");
     var ts = moment();
     watchdog.pong(ts);
@@ -21,7 +21,43 @@ test("watchdog getLastUpdate() with pong", () => {
 });
 
 test("watchdog isFatal() should be false by default", () => {
-    window.jQuery = require("jquery");
     const watchdog = require("./watchdog");
     expect(watchdog.isFatal()).toBe(false);
 });
+
+test("watchdog isFatal() should be true after deadline passes", () => {
+    const counter = require("./counter");
+    counter.init();
+
+    const config = require("./config");
+    config.newOption({
+        Cookie: "autoRefresh",
+        QueryParam: "autorefresh",
+        Selector: "#autorefresh",
+        Getter: function() {
+            return true;
+        }
+    });
+
+    const templatesMock = require("./__mocks__/templatesMock");
+    document.body.innerHTML = templatesMock.loadTemplates();
+    const templates = require("./templates");
+    templates.init();
+
+    const watchdog = require("./watchdog");
+    jest.clearAllTimers();
+    watchdog.init(1, 60); // 1s interval, 60s tolerance
+    // should be false before we pong() the first time
+    expect(watchdog.isFatal()).toBe(false);
+
+    watchdog.pong(moment());
+    // should be false after first pong since we're < maxLag
+    expect(watchdog.isFatal()).toBe(false);
+
+    // last timestamp is too old, should be true
+    var ts = moment().subtract(61, "seconds");
+    watchdog.pong(ts);
+    expect(watchdog.getLastUpdate()).toBe(ts.utc().unix());
+    jest.runTimersToTime(2 * 1000);
+    expect(watchdog.isFatal()).toBe(true);
+});