diff --git a/src/aphront/response/AphrontFileResponse.php b/src/aphront/response/AphrontFileResponse.php
index 980d1ee5dd..6508ad6020 100644
--- a/src/aphront/response/AphrontFileResponse.php
+++ b/src/aphront/response/AphrontFileResponse.php
@@ -1,167 +1,192 @@
 <?php
 
 final class AphrontFileResponse extends AphrontResponse {
 
   private $content;
   private $contentIterator;
   private $contentLength;
   private $compressResponse;
 
   private $mimeType;
+
+  /**
+   * Download filename
+   *
+   * This is NULL as default or a string.
+   *
+   * @var string|null
+   */
   private $download;
+
   private $rangeMin;
   private $rangeMax;
   private $allowOrigins = array();
 
   public function addAllowOrigin($origin) {
     $this->allowOrigins[] = $origin;
     return $this;
   }
 
+  /**
+   * Set a download filename
+   *
+   * @param $download string
+   * @return self
+   */
   public function setDownload($download) {
+
+    // Make sure we have a populated string
     if (!phutil_nonempty_string($download)) {
       $download = 'untitled';
     }
+
     $this->download = $download;
     return $this;
   }
 
+  /**
+   * Get the download filename
+   *
+   * If this was never set, NULL is given.
+   *
+   * @return string|null
+   */
   public function getDownload() {
     return $this->download;
   }
 
   public function setMimeType($mime_type) {
     $this->mimeType = $mime_type;
     return $this;
   }
 
   public function getMimeType() {
     return $this->mimeType;
   }
 
   public function setContent($content) {
     $this->setContentLength(strlen($content));
     $this->content = $content;
     return $this;
   }
 
   public function setContentIterator($iterator) {
     $this->contentIterator = $iterator;
     return $this;
   }
 
   public function buildResponseString() {
     return $this->content;
   }
 
   public function getContentIterator() {
     if ($this->contentIterator) {
       return $this->contentIterator;
     }
     return parent::getContentIterator();
   }
 
   public function setContentLength($length) {
     $this->contentLength = $length;
     return $this;
   }
 
   public function getContentLength() {
     return $this->contentLength;
   }
 
   public function setCompressResponse($compress_response) {
     $this->compressResponse = $compress_response;
     return $this;
   }
 
   public function getCompressResponse() {
     return $this->compressResponse;
   }
 
   public function setRange($min, $max) {
     $this->rangeMin = $min;
     $this->rangeMax = $max;
     return $this;
   }
 
   public function getHeaders() {
     $headers = array(
       array('Content-Type', $this->getMimeType()),
       // This tells clients that we can support requests with a "Range" header,
       // which allows downloads to be resumed, in some browsers, some of the
       // time, if the stars align.
       array('Accept-Ranges', 'bytes'),
     );
 
     if ($this->rangeMin !== null || $this->rangeMax !== null) {
       $len = $this->getContentLength();
       $min = $this->rangeMin;
 
       $max = $this->rangeMax;
       if ($max === null) {
         $max = ($len - 1);
       }
 
       $headers[] = array('Content-Range', "bytes {$min}-{$max}/{$len}");
       $content_len = ($max - $min) + 1;
     } else {
       $content_len = $this->getContentLength();
     }
 
     if (!$this->shouldCompressResponse()) {
       $headers[] = array('Content-Length', $content_len);
     }
 
-    if (strlen($this->getDownload())) {
+    if (phutil_nonempty_string($this->getDownload())) {
       $headers[] = array('X-Download-Options', 'noopen');
 
       $filename = $this->getDownload();
       $filename = addcslashes($filename, '"\\');
       $headers[] = array(
         'Content-Disposition',
         'attachment; filename="'.$filename.'"',
       );
     }
 
     if ($this->allowOrigins) {
       $headers[] = array(
         'Access-Control-Allow-Origin',
         implode(',', $this->allowOrigins),
       );
     }
 
     $headers = array_merge(parent::getHeaders(), $headers);
     return $headers;
   }
 
   protected function shouldCompressResponse() {
     return $this->getCompressResponse();
   }
 
   public function parseHTTPRange($range) {
     $begin = null;
     $end = null;
 
     $matches = null;
     if (preg_match('/^bytes=(\d+)-(\d*)$/', $range, $matches)) {
       // Note that the "Range" header specifies bytes differently than
       // we do internally: the range 0-1 has 2 bytes (byte 0 and byte 1).
       $begin = (int)$matches[1];
 
       // The "Range" may be "200-299" or "200-", meaning "until end of file".
       if (strlen($matches[2])) {
         $range_end = (int)$matches[2];
         $end = $range_end + 1;
       } else {
         $range_end = null;
       }
 
       $this->setHTTPResponseCode(206);
       $this->setRange($begin, $range_end);
     }
 
     return array($begin, $end);
   }
 
 }