diff --git a/file/lib/page/ChatMessagePage.class.php b/file/lib/page/ChatMessagePage.class.php
index 81ac24a..4b1a5d9 100644
--- a/file/lib/page/ChatMessagePage.class.php
+++ b/file/lib/page/ChatMessagePage.class.php
@@ -66,6 +66,11 @@ public function show() {
 		parent::show();
 		
 		@header('Content-type: application/json');
+		// enable gzip compression
+		if (HTTP_ENABLE_GZIP && HTTP_GZIP_LEVEL > 0 && HTTP_GZIP_LEVEL < 10 && !defined('HTTP_DISABLE_GZIP')) {
+			\wcf\util\HeaderUtil::compressOutput();
+		}
+		
 		$json = array('users' => array(), 'messages' => array());
 		
 		foreach ($this->messages as $message) {