diff --git a/extensions/firefox/components/PdfStreamConverter.js b/extensions/firefox/components/PdfStreamConverter.js
index 32143a1e5..7b3f75cc2 100644
--- a/extensions/firefox/components/PdfStreamConverter.js
+++ b/extensions/firefox/components/PdfStreamConverter.js
@@ -213,7 +213,22 @@ ChromeActions.prototype = {
     var frontWindow = Cc['@mozilla.org/embedcomp/window-watcher;1'].
                          getService(Ci.nsIWindowWatcher).activeWindow;
 
-    NetUtil.asyncFetch(blobUri, function(aInputStream, aResult) {
+    let docIsPrivate = false;
+    try {
+      docIsPrivate = this.domWindow
+                         .QueryInterface(Ci.nsIInterfaceRequestor)
+                         .getInterface(Ci.nsIWebNavigation)
+                         .QueryInterface(Ci.nsILoadContext)
+                         .usePrivateBrowsing;
+    } catch (x) {
+    }
+
+    let netChannel = NetUtil.newChannel(blobUri);
+    if ('nsIPrivateBrowsingChannel' in Ci &&
+        netChannel instanceof Ci.nsIPrivateBrowsingChannel) {
+      netChannel.setPrivate(docIsPrivate);
+    }
+    NetUtil.asyncFetch(netChannel, function(aInputStream, aResult) {
       if (!Components.isSuccessCode(aResult)) {
         if (sendResponse)
           sendResponse(true);
@@ -226,6 +241,10 @@ ChromeActions.prototype = {
       channel.setURI(originalUri);
       channel.contentStream = aInputStream;
       channel.QueryInterface(Ci.nsIChannel);
+      if ('nsIPrivateBrowsingChannel' in Ci &&
+          channel instanceof Ci.nsIPrivateBrowsingChannel) {
+        channel.setPrivate(docIsPrivate);
+      }
 
       var listener = {
         extListener: null,