diff --git a/Base/res/html/misc/cookie.html b/Base/res/html/misc/cookie.html
index 3ab6fb7721..f4a5cf4ab1 100644
--- a/Base/res/html/misc/cookie.html
+++ b/Base/res/html/misc/cookie.html
@@ -22,6 +22,8 @@
     <label for=invalid5>The cookie is too large</label>
     <br /><input id=invalid6 type=button onclick="setCookie(this.value)" value="cookie11=value11; domain=uk.gov" />
     <label for=invalid6>The cookie's domain is on the Public Suffix List</label>
+    <br /><input id=invalid7 type=button onclick="setCookie(this.value)" value="cookie12=value12; expires=Sat, 31 Feb 2060 08:10:36 GMT" />
+    <label for=invalid4>The cookie has a date that does not exist</label>
     <br />
 
     <h3>Unretrievable cookies (the browser should accept these but not display them):</h3>
diff --git a/Userland/Libraries/LibWeb/Cookie/ParsedCookie.cpp b/Userland/Libraries/LibWeb/Cookie/ParsedCookie.cpp
index 3729947ab3..2c171c377b 100644
--- a/Userland/Libraries/LibWeb/Cookie/ParsedCookie.cpp
+++ b/Userland/Libraries/LibWeb/Cookie/ParsedCookie.cpp
@@ -345,7 +345,9 @@ Optional<UnixDateTime> parse_date_time(StringView date_string)
     // 6. Let the parsed-cookie-date be the date whose day-of-month, month, year, hour, minute, and second (in UTC) are the
     //    day-of-month-value, the month-value, the year-value, the hour-value, the minute-value, and the second-value, respectively.
     //    If no such date exists, abort these steps and fail to parse the cookie-date.
-    // FIXME: Fail on dates that do not exist.
+    if (day_of_month > static_cast<unsigned int>(days_in_month(year, month)))
+        return {};
+
     // FIXME: This currently uses UNIX time, which is not equivalent to UTC due to leap seconds.
     auto parsed_cookie_date = UnixDateTime::from_unix_time_parts(year, month, day_of_month, hour, minute, second, 0);