diff --git a/src/aphront/response/AphrontFileResponse.php b/src/aphront/response/AphrontFileResponse.php
--- a/src/aphront/response/AphrontFileResponse.php
+++ b/src/aphront/response/AphrontFileResponse.php
@@ -105,7 +105,7 @@
     }
 
     if (!$this->shouldCompressResponse()) {
-      $headers[] = array('Content-Length', $this->getContentLength());
+      $headers[] = array('Content-Length', $content_len);
     }
 
     if (strlen($this->getDownload())) {