diff --git a/404.html b/404.html
index 0ca7ed1..4b93594 100644
--- a/404.html
+++ b/404.html
@@ -19,7 +19,7 @@
   <p class="output">Please try to <a href="javascript:history.back()">go back</a> or <a href="/">return to the homepage</a>.</p>
   <p class="output">Good luck.</p>
 </div>
-<script> 
+<script type="module"> 
       const disabledKeys = ["c", "C", "x", "J", "u", "I"]; // keys that will be disabled
       const showAlert = e => {
         e.preventDefault(); // preventing its default behaviour