diff --git a/extensions/firefox/content/PdfStreamConverter.jsm b/extensions/firefox/content/PdfStreamConverter.jsm
index 61e0c16c3..14b12becd 100644
--- a/extensions/firefox/content/PdfStreamConverter.jsm
+++ b/extensions/firefox/content/PdfStreamConverter.jsm
@@ -794,7 +794,7 @@ RequestListener.prototype.receive = function(event) {
   var response;
   if (sync) {
     response = actions[action].call(this.actions, data);
-    event.detail.response = response;
+    event.detail.response = makeContentReadable(response, doc.defaultView);
   } else {
     if (!event.detail.responseExpected) {
       doc.documentElement.removeChild(message);