diff --git a/tests/test.keyboard.js b/tests/test.keyboard.js
index 135c5981b..11c8b6eb7 100644
--- a/tests/test.keyboard.js
+++ b/tests/test.keyboard.js
@@ -478,6 +478,22 @@ describe('Key Event Handling', function () {
             expect(kbd.onkeyevent).to.not.have.been.called;
         });
 
+        it('should release ControlLeft on blur', function () {
+            const kbd = new Keyboard(document);
+            kbd.onkeyevent = sinon.spy();
+            kbd._handleKeyDown(keyevent('keydown', {code: 'ControlLeft', key: 'Control', location: 1}));
+            expect(kbd.onkeyevent).to.not.have.been.called;
+            kbd._allKeysUp();
+            expect(kbd.onkeyevent).to.have.been.calledTwice;
+            expect(kbd.onkeyevent.firstCall).to.have.been.calledWith(0xffe3, "ControlLeft", true);
+            expect(kbd.onkeyevent.secondCall).to.have.been.calledWith(0xffe3, "ControlLeft", false);
+
+            // Check that the timer is properly dead
+            kbd.onkeyevent.resetHistory();
+            this.clock.tick(100);
+            expect(kbd.onkeyevent).to.not.have.been.called;
+        });
+
         it('should generate AltGraph for quick Ctrl+Alt sequence', function () {
             const kbd = new Keyboard(document);
             kbd.onkeyevent = sinon.spy();