User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.11; rv:51.0) Gecko/20100101 Firefox/51.0 Build ID: 20170125094131 Steps to reproduce: Using the JavaScript console of the default Firefox developer tools I set a cookie that expires after 30 seconds using following JavaScript: document.cookie = "test=123; expires=" + new Date(Date.now() + 30 * 1000).toUTCString(); Actual results: The cookie appeared in the "Storage"-tab of the Developer Tools in the Cookies-area. After waiting (more than 30 seconds), relogging and restarting of firefox and my PC, the cookie, that is now expired, is still displayed in the cookie list of the Developer Tools. The expired cookie is also still shown in the window "Cookies" (Tools>Page Info->Display Cookies). Accessing it via "document.cookie" is not possible anymore. Expected results: I expect from a expired cookie to disappear from the cookie list in the developer tools (like it does in other Browsers e.g. Chrome and Safari).