diff --git a/pdf.js b/pdf.js
index 9905d73..c05fe3d 100644
--- a/pdf.js
+++ b/pdf.js
@@ -13201,7 +13201,11 @@ var OverlayManager = {
           !(container = element.parentNode)) {
         throw new Error('Not enough parameters.');
       } else if (this.overlays[name]) {
-        throw new Error('The overlay is already registered.');
+        if (this.active !== name) {
+          this.unregister(name);
+        } else {
+          throw new Error('The overlay is already registered and active.');
+        }
       }
       this.overlays[name] = { element: element,
                               container: container,
diff --git a/pdf.js.patch b/pdf.js.patch
index 507c761..45ce1d9 100644
--- a/pdf.js.patch
+++ b/pdf.js.patch
@@ -1,54 +1,110 @@
-829c829,831
-<       console.warn('#' + key + ' is undefined.');
----
->       if (Object.keys(gL10nData).length > 0) {
->         console.warn('#' + key + ' is undefined.');
->       }
-10292,10295c10294,10304
-< PDFJS.imageResourcesPath = './images/';
-<   PDFJS.workerSrc = '../build/pdf.worker.js';
-<   PDFJS.cMapUrl = '../web/cmaps/';
-<   PDFJS.cMapPacked = true;
----
-> var scriptTagContainer = document.body ||
->                          document.getElementsByTagName('head')[0];
-> var pdfjsSrc = scriptTagContainer.lastChild.src;
-> 
-> if (pdfjsSrc) {
->   PDFJS.imageResourcesPath = pdfjsSrc.replace(/pdf\.js$/i, 'images/');
->   PDFJS.workerSrc = pdfjsSrc.replace(/pdf\.js$/i, 'pdf.worker.js');
->   PDFJS.cMapUrl = pdfjsSrc.replace(/pdf\.js$/i, 'cmaps/');
-> }
-> 
-> PDFJS.cMapPacked = true;
-11743c11752
-<       return this.pdfDocument.numPages;
----
->       return this.pdfDocument ? this.pdfDocument.numPages : 0;
-16488c16497
-<     return this.pdfDocument.numPages;
----
->     return this.pdfDocument ? this.pdfDocument.numPages : 0;
-17024c17033,17035
-<     this.pdfDocument.cleanup();
----
->     if (this.pdfDocument) {
->       this.pdfDocument.cleanup();
->     }
-17465c17476,17481
-< document.addEventListener('DOMContentLoaded', webViewerLoad, true);
----
-> // document.addEventListener('DOMContentLoaded', webViewerLoad, true);
-> PDFJS.webViewerLoad = function (src) {
->   if (src) DEFAULT_URL = src;
-> 
->   webViewerLoad();
-> }
-17588c17604
-<   if (PDFViewerApplication.pdfHistory.isHashChangeUnlocked) {
----
->   if (PDFViewerApplication.pdfHistory && PDFViewerApplication.pdfHistory.isHashChangeUnlocked) {
-17740a17757,17759
->   // Ignore mousewheel event if pdfViewer isn't loaded
->   if (!PDFViewerApplication.pdfViewer) return;
->   
+--- pdf.orig.js	2015-11-19 00:10:27.980871274 -0400
++++ pdf.js	2015-11-19 00:27:00.668845816 -0400
+@@ -826,7 +826,9 @@
+   function getL10nData(key, args, fallback) {
+     var data = gL10nData[key];
+     if (!data) {
+-      console.warn('#' + key + ' is undefined.');
++      if (Object.keys(gL10nData).length > 0) {
++        console.warn('#' + key + ' is undefined.');
++      }
+       if (!fallback) {
+         return null;
+       }
+@@ -10289,10 +10291,17 @@
+ var PAGE_NUMBER_LOADING_INDICATOR = 'visiblePageIsLoading';
+ var DISABLE_AUTO_FETCH_LOADING_BAR_TIMEOUT = 5000;
+ 
+-PDFJS.imageResourcesPath = './images/';
+-  PDFJS.workerSrc = '../build/pdf.worker.js';
+-  PDFJS.cMapUrl = '../web/cmaps/';
+-  PDFJS.cMapPacked = true;
++var scriptTagContainer = document.body ||
++                         document.getElementsByTagName('head')[0];
++var pdfjsSrc = scriptTagContainer.lastChild.src;
++
++if (pdfjsSrc) {
++  PDFJS.imageResourcesPath = pdfjsSrc.replace(/pdf\.js$/i, 'images/');
++  PDFJS.workerSrc = pdfjsSrc.replace(/pdf\.js$/i, 'pdf.worker.js');
++  PDFJS.cMapUrl = pdfjsSrc.replace(/pdf\.js$/i, 'cmaps/');
++}
++
++PDFJS.cMapPacked = true;
+ 
+ var mozL10n = document.mozL10n || document.webL10n;
+ 
+@@ -11740,7 +11749,7 @@
+      * @returns {number}
+      */
+     get pagesCount() {
+-      return this.pdfDocument.numPages;
++      return this.pdfDocument ? this.pdfDocument.numPages : 0;
+     },
+ 
+     /**
+@@ -13192,7 +13201,11 @@
+           !(container = element.parentNode)) {
+         throw new Error('Not enough parameters.');
+       } else if (this.overlays[name]) {
+-        throw new Error('The overlay is already registered.');
++        if (this.active !== name) {
++          this.unregister(name);
++        } else {
++          throw new Error('The overlay is already registered and active.');
++        }
+       }
+       this.overlays[name] = { element: element,
+                               container: container,
+@@ -16485,7 +16498,7 @@
+   },
+ 
+   get pagesCount() {
+-    return this.pdfDocument.numPages;
++    return this.pdfDocument ? this.pdfDocument.numPages : 0;
+   },
+ 
+   set page(val) {
+@@ -17021,7 +17034,9 @@
+   cleanup: function pdfViewCleanup() {
+     this.pdfViewer.cleanup();
+     this.pdfThumbnailViewer.cleanup();
+-    this.pdfDocument.cleanup();
++    if (this.pdfDocument) {
++      this.pdfDocument.cleanup();
++    }
+   },
+ 
+   forceRendering: function pdfViewForceRendering() {
+@@ -17462,7 +17477,12 @@
+   }
+ }
+ 
+-document.addEventListener('DOMContentLoaded', webViewerLoad, true);
++// document.addEventListener('DOMContentLoaded', webViewerLoad, true);
++PDFJS.webViewerLoad = function (src) {
++  if (src) DEFAULT_URL = src;
++
++  webViewerLoad();
++}
+ 
+ document.addEventListener('pagerendered', function (e) {
+   var pageNumber = e.detail.pageNumber;
+@@ -17585,7 +17605,7 @@
+ });
+ 
+ window.addEventListener('hashchange', function webViewerHashchange(evt) {
+-  if (PDFViewerApplication.pdfHistory.isHashChangeUnlocked) {
++  if (PDFViewerApplication.pdfHistory && PDFViewerApplication.pdfHistory.isHashChangeUnlocked) {
+     var hash = document.location.hash.substring(1);
+     if (!hash) {
+       return;
+@@ -17738,6 +17758,9 @@
+ }, true);
+ 
+ function handleMouseWheel(evt) {
++  // Ignore mousewheel event if pdfViewer isn't loaded
++  if (!PDFViewerApplication.pdfViewer) return;
++  
+   var MOUSE_WHEEL_DELTA_FACTOR = 40;
+   var ticks = (evt.type === 'DOMMouseScroll') ? -evt.detail :
+               evt.wheelDelta / MOUSE_WHEEL_DELTA_FACTOR;