diff --git a/browser/extensions/mortar/host/common/ppapi-runtime.jsm b/browser/extensions/mortar/host/common/ppapi-runtime.jsm
index 6ecc506b6b01..874d71d0df13 100644
--- a/browser/extensions/mortar/host/common/ppapi-runtime.jsm
+++ b/browser/extensions/mortar/host/common/ppapi-runtime.jsm
@@ -1811,7 +1811,8 @@ class PPAPIInstance {
         this.mm.sendAsyncMessage("ppapi.js:setFullscreen", message.fullscreen);
         break;
       case 'save':
-        this.mm.sendAsyncMessage("ppapipdf.js:save");
+        this.mm.sendAsyncMessage("ppapipdf.js:save", {
+          url: this.info.url });
         break;
       case 'setHash':
         this.mm.sendAsyncMessage("ppapipdf.js:setHash", message.hash);
diff --git a/browser/extensions/mortar/host/pdf/ppapi-content-sandbox.js b/browser/extensions/mortar/host/pdf/ppapi-content-sandbox.js
index ea5754ab49ad..b2b30dd94bcc 100644
--- a/browser/extensions/mortar/host/pdf/ppapi-content-sandbox.js
+++ b/browser/extensions/mortar/host/pdf/ppapi-content-sandbox.js
@@ -222,8 +222,8 @@ mm.addMessageListener("ppapipdf.js:openLink", ({data}) => {
   }
 });
 
-mm.addMessageListener("ppapipdf.js:save", () => {
-  let url = containerWindow.document.location;
+mm.addMessageListener("ppapipdf.js:save", ({ data }) => {
+  let url = new containerWindow.URL(data.url);
   let filename = getFileName(url);
   let originalUri = NetUtil.newURI(url.href);
   let extHelperAppSvc =