diff --git a/phpBB/adm/style/acp_avatar_options_upload.html b/phpBB/adm/style/acp_avatar_options_upload.html
index 4b067c00f8..666950e0ae 100644
--- a/phpBB/adm/style/acp_avatar_options_upload.html
+++ b/phpBB/adm/style/acp_avatar_options_upload.html
@@ -1,6 +1,6 @@
 <dl>
 	<dt><label for="avatar_upload_file">{L_UPLOAD_AVATAR_FILE}{L_COLON}</label></dt>
-	<dd><input type="hidden" name="MAX_FILE_SIZE" value="{AVATAR_UPLOAD_SIZE}" /><input type="file" name="avatar_upload_file" id="avatar_upload_file" class="inputbox autowidth" accept="{% for EXTENSION in AVATAR_ALLOWED_EXTENSIONS %}.{{ EXTENSION }}{% if not loop.last %},{% endif %}{% endfor %}" /></dd>
+	<dd><input type="hidden" name="MAX_FILE_SIZE" value="{AVATAR_UPLOAD_SIZE}" /><input type="file" name="avatar_upload_file" id="avatar_upload_file" class="inputbox autowidth" accept="{{ AVATAR_ALLOWED_EXTENSIONS }}" /></dd>
 </dl>
 
 <!-- IF S_UPLOAD_AVATAR_URL -->
diff --git a/phpBB/phpbb/avatar/driver/upload.php b/phpBB/phpbb/avatar/driver/upload.php
index d6853694b6..73d5e8fcf8 100644
--- a/phpBB/phpbb/avatar/driver/upload.php
+++ b/phpBB/phpbb/avatar/driver/upload.php
@@ -92,7 +92,7 @@ class upload extends \phpbb\avatar\driver\driver
 		$template->assign_vars(array(
 			'S_UPLOAD_AVATAR_URL' => ($this->config['allow_avatar_remote_upload']) ? true : false,
 			'AVATAR_UPLOAD_SIZE' => $this->config['avatar_filesize'],
-			'AVATAR_ALLOWED_EXTENSIONS' => $this->allowed_extensions,
+			'AVATAR_ALLOWED_EXTENSIONS' => implode(',', preg_replace('/^/', '.', $this->allowed_extensions)),
 		));
 
 		return true;
diff --git a/phpBB/styles/prosilver/template/ucp_avatar_options_upload.html b/phpBB/styles/prosilver/template/ucp_avatar_options_upload.html
index 4b067c00f8..666950e0ae 100644
--- a/phpBB/styles/prosilver/template/ucp_avatar_options_upload.html
+++ b/phpBB/styles/prosilver/template/ucp_avatar_options_upload.html
@@ -1,6 +1,6 @@
 <dl>
 	<dt><label for="avatar_upload_file">{L_UPLOAD_AVATAR_FILE}{L_COLON}</label></dt>
-	<dd><input type="hidden" name="MAX_FILE_SIZE" value="{AVATAR_UPLOAD_SIZE}" /><input type="file" name="avatar_upload_file" id="avatar_upload_file" class="inputbox autowidth" accept="{% for EXTENSION in AVATAR_ALLOWED_EXTENSIONS %}.{{ EXTENSION }}{% if not loop.last %},{% endif %}{% endfor %}" /></dd>
+	<dd><input type="hidden" name="MAX_FILE_SIZE" value="{AVATAR_UPLOAD_SIZE}" /><input type="file" name="avatar_upload_file" id="avatar_upload_file" class="inputbox autowidth" accept="{{ AVATAR_ALLOWED_EXTENSIONS }}" /></dd>
 </dl>
 
 <!-- IF S_UPLOAD_AVATAR_URL -->