diff --git a/scripts/advanced.php b/scripts/advanced.php
index 7640091..440f16e 100644
--- a/scripts/advanced.php
+++ b/scripts/advanced.php
@@ -277,7 +277,7 @@ foreach($formats as $format){
       <h3>BirdNET-Pi Password</h3>
       <p>This password will protect your "Tools" page and "Live Audio" stream.</p>
       <label for="caddy_pwd">Password: </label>
-      <input style="width:40ch" name="caddy_pwd" id="caddy_pwd" type="password" value="<?php print($newconfig['CADDY_PWD']);?>" /><span id="showpassword" onmouseover="document.getElementById('caddy_pwd').type='text';" onmouseout="document.getElementById('caddy_pwd').type='password';">show</span><br>
+      <input style="width:40ch" name="caddy_pwd" id="caddy_pwd" type="password" pattern="[A-Za-z0-9]+" title="Password must be alphanumeric (A-Z, 0-9)" value="<?php print($newconfig['CADDY_PWD']);?>" /><span id="showpassword" onmouseover="document.getElementById('caddy_pwd').type='text';" onmouseout="document.getElementById('caddy_pwd').type='password';">show</span><br>
       <h3>Custom URL</h3>
       <p>When you update the URL below, the web server will reload, so be sure to wait at least 30 seconds and then go to your new URL.</p>
       <label for="birdnetpi_url">BirdNET-Pi URL: </label>