diff --git a/extensions/amp-lightbox/0.1/test/test-amp-lightbox.js b/extensions/amp-lightbox/0.1/test/test-amp-lightbox.js
index f797c77ba44d..0ccafd6c9340 100644
--- a/extensions/amp-lightbox/0.1/test/test-amp-lightbox.js
+++ b/extensions/amp-lightbox/0.1/test/test-amp-lightbox.js
@@ -114,7 +114,7 @@ describes.realWin(
       const setupCloseSpy = env.sandbox.spy(impl, 'close');
 
       await impl.open_({caller: sourceElement});
-      impl.closeWatcher_.signalClosed();
+      impl.closeWatcher_.requestClose();
       expect(setupCloseSpy).to.be.called;
     });
 
diff --git a/src/utils/close-watcher-impl.js b/src/utils/close-watcher-impl.js
index fa525552049c..320f18793daf 100644
--- a/src/utils/close-watcher-impl.js
+++ b/src/utils/close-watcher-impl.js
@@ -67,11 +67,11 @@ export class CloseWatcherImpl {
 
   /**
    * Signals to the close watcher to close the modal.
-   * See `CloseWatcher.signalClosed`.
+   * See `CloseWatcher.requestClose`.
    */
-  signalClosed() {
+  requestClose() {
     if (this.watcher_) {
-      this.watcher_.signalClosed();
+      this.watcher_.requestClose();
     } else if (this.handler_) {
       const handler = this.handler_;
       handler();
@@ -106,7 +106,7 @@ export class CloseWatcherImpl {
   closeOnEscape_(event) {
     if (event.key == Keys_Enum.ESCAPE) {
       event.preventDefault();
-      this.signalClosed();
+      this.requestClose();
     }
   }
 }
diff --git a/src/utils/close-watcher.extern.js b/src/utils/close-watcher.extern.js
index 4a208a563c7c..12ee76aad07f 100644
--- a/src/utils/close-watcher.extern.js
+++ b/src/utils/close-watcher.extern.js
@@ -12,7 +12,7 @@ function CloseWatcher() {}
 
 CloseWatcher.prototype.destroy = function () {};
 
-CloseWatcher.prototype.signalClosed = function () {};
+CloseWatcher.prototype.requestClose = function () {};
 
 /** @type {?function(!Event)} */
 CloseWatcher.prototype.onclose;
diff --git a/test/unit/utils/test-close-watcher-impl.js b/test/unit/utils/test-close-watcher-impl.js
index 970370eee754..fb1e1067c3aa 100644
--- a/test/unit/utils/test-close-watcher-impl.js
+++ b/test/unit/utils/test-close-watcher-impl.js
@@ -24,46 +24,57 @@ describes.realWin('#CloseWatcherImpl', {amp: true}, (env) => {
     historyMock.verify();
   });
 
-  // TODO(#40214): fix flaky test.
-  it.skip('should push and pop history state', async () => {
-    historyMock.expects('push').resolves('H1').once();
-    historyMock.expects('pop').withArgs('H1').once();
-    const watcher = new CloseWatcherImpl(ampdoc, handler);
-    await Promise.resolve('H1');
-    watcher.signalClosed();
-    expect(handler).to.be.calledOnce;
-  });
+  it.configure()
+    .if(() => 'CloseWatcher' in window)
+    .run('should call the handler on requestClose', async () => {
+      const watcher = new CloseWatcherImpl(ampdoc, handler);
+      watcher.requestClose();
+      expect(handler).to.be.calledOnce;
+    });
 
-  // TODO(#40214): fix flaky test.
-  it.skip('should trigger on history pop', async () => {
-    let popHandler;
-    historyMock
-      .expects('push')
-      .withArgs(
-        env.sandbox.match((a) => {
-          popHandler = a;
-          return true;
-        })
-      )
-      .resolves('H1')
-      .once();
-    new CloseWatcherImpl(ampdoc, handler);
-    await Promise.resolve('H1');
-    expect(popHandler).to.exist;
-    popHandler();
-    expect(handler).to.be.calledOnce;
-  });
+  it.configure()
+    .if(() => !('CloseWatcher' in window))
+    .run('should push and pop history state', async () => {
+      historyMock.expects('push').resolves('H1').once();
+      historyMock.expects('pop').withArgs('H1').once();
+      const watcher = new CloseWatcherImpl(ampdoc, handler);
+      await Promise.resolve('H1');
+      watcher.requestClose();
+      expect(handler).to.be.calledOnce;
+    });
 
-  // TODO(#40214): fix flaky test.
-  it.skip('should trigger on ESC key', async () => {
-    historyMock.expects('push').resolves('H1').once();
-    historyMock.expects('pop').withArgs('H1').once();
-    new CloseWatcherImpl(ampdoc, handler);
-    await Promise.resolve('H1');
+  it.configure()
+    .if(() => !('CloseWatcher' in window))
+    .run('should trigger on history pop', async () => {
+      let popHandler;
+      historyMock
+        .expects('push')
+        .withArgs(
+          env.sandbox.match((a) => {
+            popHandler = a;
+            return true;
+          })
+        )
+        .resolves('H1')
+        .once();
+      new CloseWatcherImpl(ampdoc, handler);
+      await Promise.resolve('H1');
+      expect(popHandler).to.exist;
+      popHandler();
+      expect(handler).to.be.calledOnce;
+    });
 
-    doc.documentElement.dispatchEvent(
-      new KeyboardEvent('keydown', {key: Keys_Enum.ESCAPE})
-    );
-    expect(handler).to.be.calledOnce;
-  });
+  it.configure()
+    .if(() => !('CloseWatcher' in window))
+    .run('should trigger on ESC key', async () => {
+      historyMock.expects('push').resolves('H1').once();
+      historyMock.expects('pop').withArgs('H1').once();
+      new CloseWatcherImpl(ampdoc, handler);
+      await Promise.resolve('H1');
+
+      doc.documentElement.dispatchEvent(
+        new KeyboardEvent('keydown', {key: Keys_Enum.ESCAPE})
+      );
+      expect(handler).to.be.calledOnce;
+    });
 });