diff --git a/.web-extension-id b/.web-extension-id
new file mode 100644
index 0000000..3d19496
--- /dev/null
+++ b/.web-extension-id
@@ -0,0 +1,3 @@
+# This file was created by https://github.com/mozilla/web-ext
+# Your auto-generated extension ID for addons.mozilla.org is:
+{dc4e3b3d-bbb2-4dee-be69-752b75e9e425}
\ No newline at end of file
diff --git a/js/background.js b/js/background.js
index 1b00b56..3f92f1f 100644
--- a/js/background.js
+++ b/js/background.js
@@ -24,13 +24,12 @@ function fetchChapters() {
     });});
 }
 
-function handleMessage(message, sender, respond) {
+function handleMessage(message, sender) {
     if (message.msg == "getChapters") {
-	fetchChapters().then(chapters => respond(chapters)).catch(() => {
-	    respond();
-	});
-	return true;
+	return fetchChapters();
     }
+
+    return true;
 }
 
 browser.runtime.onMessage.addListener(handleMessage);
diff --git a/js/main.js b/js/main.js
index f0d791d..ab50532 100644
--- a/js/main.js
+++ b/js/main.js
@@ -163,6 +163,7 @@ function linkFootnotes() {
 
 // Let's apply that stuff.
 loadChapters().then(newChapters => {
+    console.log(newChapters);
     chapters = newChapters;
     setUpNumbering();
 });
diff --git a/js/webpoly.js b/js/webpoly.js
new file mode 100644
index 0000000..86ca59d
--- /dev/null
+++ b/js/webpoly.js
@@ -0,0 +1,9 @@
+(function(a,b){if("function"==typeof define&&define.amd)define("webextension-polyfill",["module"],b);else if("undefined"!=typeof exports)b(module);else{var c={exports:{}};b(c),a.browser=c.exports}})(this,function(a){"use strict";if("undefined"==typeof browser||Object.getPrototypeOf(browser)!==Object.prototype){a.exports=(()=>{const e={alarms:{clear:{minArgs:0,maxArgs:1},clearAll:{minArgs:0,maxArgs:0},get:{minArgs:0,maxArgs:1},getAll:{minArgs:0,maxArgs:0}},bookmarks:{create:{minArgs:1,maxArgs:1},get:{minArgs:1,maxArgs:1},getChildren:{minArgs:1,maxArgs:1},getRecent:{minArgs:1,maxArgs:1},getSubTree:{minArgs:1,maxArgs:1},getTree:{minArgs:0,maxArgs:0},move:{minArgs:2,maxArgs:2},remove:{minArgs:1,maxArgs:1},removeTree:{minArgs:1,maxArgs:1},search:{minArgs:1,maxArgs:1},update:{minArgs:2,maxArgs:2}},browserAction:{disable:{minArgs:0,maxArgs:1,fallbackToNoCallback:!0},enable:{minArgs:0,maxArgs:1,fallbackToNoCallback:!0},getBadgeBackgroundColor:{minArgs:1,maxArgs:1},getBadgeText:{minArgs:1,maxArgs:1},getPopup:{minArgs:1,maxArgs:1},getTitle:{minArgs:1,maxArgs:1},openPopup:{minArgs:0,maxArgs:0},setBadgeBackgroundColor:{minArgs:1,maxArgs:1,fallbackToNoCallback:!0},setBadgeText:{minArgs:1,maxArgs:1,fallbackToNoCallback:!0},setIcon:{minArgs:1,maxArgs:1},setPopup:{minArgs:1,maxArgs:1,fallbackToNoCallback:!0},setTitle:{minArgs:1,maxArgs:1,fallbackToNoCallback:!0}},browsingData:{remove:{minArgs:2,maxArgs:2},removeCache:{minArgs:1,maxArgs:1},removeCookies:{minArgs:1,maxArgs:1},removeDownloads:{minArgs:1,maxArgs:1},removeFormData:{minArgs:1,maxArgs:1},removeHistory:{minArgs:1,maxArgs:1},removeLocalStorage:{minArgs:1,maxArgs:1},removePasswords:{minArgs:1,maxArgs:1},removePluginData:{minArgs:1,maxArgs:1},settings:{minArgs:0,maxArgs:0}},commands:{getAll:{minArgs:0,maxArgs:0}},contextMenus:{remove:{minArgs:1,maxArgs:1},removeAll:{minArgs:0,maxArgs:0},update:{minArgs:2,maxArgs:2}},cookies:{get:{minArgs:1,maxArgs:1},getAll:{minArgs:1,maxArgs:1},getAllCookieStores:{minArgs:0,maxArgs:0},remove:{minArgs:1,maxArgs:1},set:{minArgs:1,maxArgs:1}},devtools:{inspectedWindow:{eval:{minArgs:1,maxArgs:2}},panels:{create:{minArgs:3,maxArgs:3,singleCallbackArg:!0}}},downloads:{cancel:{minArgs:1,maxArgs:1},download:{minArgs:1,maxArgs:1},erase:{minArgs:1,maxArgs:1},getFileIcon:{minArgs:1,maxArgs:2},open:{minArgs:1,maxArgs:1,fallbackToNoCallback:!0},pause:{minArgs:1,maxArgs:1},removeFile:{minArgs:1,maxArgs:1},resume:{minArgs:1,maxArgs:1},search:{minArgs:1,maxArgs:1},show:{minArgs:1,maxArgs:1,fallbackToNoCallback:!0}},extension:{isAllowedFileSchemeAccess:{minArgs:0,maxArgs:0},isAllowedIncognitoAccess:{minArgs:0,maxArgs:0}},history:{addUrl:{minArgs:1,maxArgs:1},deleteAll:{minArgs:0,maxArgs:0},deleteRange:{minArgs:1,maxArgs:1},deleteUrl:{minArgs:1,maxArgs:1},getVisits:{minArgs:1,maxArgs:1},search:{minArgs:1,maxArgs:1}},i18n:{detectLanguage:{minArgs:1,maxArgs:1},getAcceptLanguages:{minArgs:0,maxArgs:0}},identity:{launchWebAuthFlow:{minArgs:1,maxArgs:1}},idle:{queryState:{minArgs:1,maxArgs:1}},management:{get:{minArgs:1,maxArgs:1},getAll:{minArgs:0,maxArgs:0},getSelf:{minArgs:0,maxArgs:0},setEnabled:{minArgs:2,maxArgs:2},uninstallSelf:{minArgs:0,maxArgs:1}},notifications:{clear:{minArgs:1,maxArgs:1},create:{minArgs:1,maxArgs:2},getAll:{minArgs:0,maxArgs:0},getPermissionLevel:{minArgs:0,maxArgs:0},update:{minArgs:2,maxArgs:2}},pageAction:{getPopup:{minArgs:1,maxArgs:1},getTitle:{minArgs:1,maxArgs:1},hide:{minArgs:1,maxArgs:1,fallbackToNoCallback:!0},setIcon:{minArgs:1,maxArgs:1},setPopup:{minArgs:1,maxArgs:1,fallbackToNoCallback:!0},setTitle:{minArgs:1,maxArgs:1,fallbackToNoCallback:!0},show:{minArgs:1,maxArgs:1,fallbackToNoCallback:!0}},permissions:{contains:{minArgs:1,maxArgs:1},getAll:{minArgs:0,maxArgs:0},remove:{minArgs:1,maxArgs:1},request:{minArgs:1,maxArgs:1}},runtime:{getBackgroundPage:{minArgs:0,maxArgs:0},getBrowserInfo:{minArgs:0,maxArgs:0},getPlatformInfo:{minArgs:0,maxArgs:0},openOptionsPage:{minArgs:0,maxArgs:0},requestUpdateCheck:{minArgs:0,maxArgs:0},sendMessage:{minArgs:1,maxArgs:3},sendNativeMessage:{minArgs:2,maxArgs:2},setUninstallURL:{minArgs:1,maxArgs:1}},sessions:{getDevices:{minArgs:0,maxArgs:1},getRecentlyClosed:{minArgs:0,maxArgs:1},restore:{minArgs:0,maxArgs:1}},storage:{local:{clear:{minArgs:0,maxArgs:0},get:{minArgs:0,maxArgs:1},getBytesInUse:{minArgs:0,maxArgs:1},remove:{minArgs:1,maxArgs:1},set:{minArgs:1,maxArgs:1}},managed:{get:{minArgs:0,maxArgs:1},getBytesInUse:{minArgs:0,maxArgs:1}},sync:{clear:{minArgs:0,maxArgs:0},get:{minArgs:0,maxArgs:1},getBytesInUse:{minArgs:0,maxArgs:1},remove:{minArgs:1,maxArgs:1},set:{minArgs:1,maxArgs:1}}},tabs:{captureVisibleTab:{minArgs:0,maxArgs:2},create:{minArgs:1,maxArgs:1},detectLanguage:{minArgs:0,maxArgs:1},discard:{minArgs:0,maxArgs:1},duplicate:{minArgs:1,maxArgs:1},executeScript:{minArgs:1,maxArgs:2},get:{minArgs:1,maxArgs:1},getCurrent:{minArgs:0,maxArgs:0},getZoom:{minArgs:0,maxArgs:1},getZoomSettings:{minArgs:0,maxArgs:1},highlight:{minArgs:1,maxArgs:1},insertCSS:{minArgs:1,maxArgs:2},move:{minArgs:2,maxArgs:2},query:{minArgs:1,maxArgs:1},reload:{minArgs:0,maxArgs:2},remove:{minArgs:1,maxArgs:1},removeCSS:{minArgs:1,maxArgs:2},sendMessage:{minArgs:2,maxArgs:3},setZoom:{minArgs:1,maxArgs:2},setZoomSettings:{minArgs:1,maxArgs:2},update:{minArgs:1,maxArgs:2}},topSites:{get:{minArgs:0,maxArgs:0}},webNavigation:{getAllFrames:{minArgs:1,maxArgs:1},getFrame:{minArgs:1,maxArgs:1}},webRequest:{handlerBehaviorChanged:{minArgs:0,maxArgs:0}},windows:{create:{minArgs:0,maxArgs:1},get:{minArgs:1,maxArgs:2},getAll:{minArgs:0,maxArgs:1},getCurrent:{minArgs:0,maxArgs:1},getLastFocused:{minArgs:0,maxArgs:1},remove:{minArgs:1,maxArgs:1},update:{minArgs:2,maxArgs:2}}};if(0===Object.keys(e).length)throw new Error("api-metadata.json has not been included in browser-polyfill");class f extends WeakMap{constructor(u,v=void 0){super(v),this.createItem=u}get(u){return this.has(u)||this.set(u,this.createItem(u)),super.get(u)}}const g=u=>{return u&&"object"==typeof u&&"function"==typeof u.then},h=(u,v)=>{return(...w)=>{chrome.runtime.lastError?u.reject(chrome.runtime.lastError):v.singleCallbackArg||1>=w.length?u.resolve(w[0]):u.resolve(w)}},i=u=>1==u?"argument":"arguments",j=(u,v)=>{return function(x,...y){if(y.length<v.minArgs)throw new Error(`Expected at least ${v.minArgs} ${i(v.minArgs)} for ${u}(), got ${y.length}`);if(y.length>v.maxArgs)throw new Error(`Expected at most ${v.maxArgs} ${i(v.maxArgs)} for ${u}(), got ${y.length}`);return new Promise((z,A)=>{if(v.fallbackToNoCallback)try{x[u](...y,h({resolve:z,reject:A},v))}catch(B){console.warn(`${u} API method doesn't seem to support the callback parameter, `+"falling back to call it without a callback: ",B),x[u](...y),v.fallbackToNoCallback=!1,v.noCallback=!0,z()}else v.noCallback?(x[u](...y),z()):x[u](...y,h({resolve:z,reject:A},v))})}},k=(u,v,w)=>{return new Proxy(v,{apply(x,y,z){return w.call(y,u,...z)}})};let l=Function.call.bind(Object.prototype.hasOwnProperty);const m=(u,v={},w={})=>{let x=Object.create(null),y={has(A,B){return B in u||B in x},get(A,B){if(B in x)return x[B];if(B in u){let D=u[B];if("function"==typeof D){if("function"==typeof v[B])D=k(u,u[B],v[B]);else if(l(w,B)){let E=j(B,w[B]);D=k(u,u[B],E)}else D=D.bind(u);}else if("object"==typeof D&&null!==D&&(l(v,B)||l(w,B)))D=m(D,v[B],w[B]);else return Object.defineProperty(x,B,{configurable:!0,enumerable:!0,get(){return u[B]},set(E){u[B]=E}}),D;return x[B]=D,D}},set(A,B,C){return B in x?x[B]=C:u[B]=C,!0},defineProperty(A,B,C){return Reflect.defineProperty(x,B,C)},deleteProperty(A,B){return Reflect.deleteProperty(x,B)}},z=Object.create(u);return new Proxy(z,y)},n=u=>({addListener(v,w,...x){v.addListener(u.get(w),...x)},hasListener(v,w){return v.hasListener(u.get(w))},removeListener(v,w){v.removeListener(u.get(w))}});let o=!1;const p=new f(u=>{return"function"==typeof u?function(w,x,y){let A,C,z=!1,B=new Promise(F=>{A=function(G){o||(console.warn("Returning a Promise is the preferred way to send a reply from an onMessage/onMessageExternal listener, as the sendResponse will be removed from the specs (See https://developer.mozilla.org/docs/Mozilla/Add-ons/WebExtensions/API/runtime/onMessage)",new Error().stack),o=!0),z=!0,F(G)}});try{C=u(w,x,A)}catch(F){C=Promise.reject(F)}const D=!0!==C&&g(C);if(!0!==C&&!D&&!z)return!1;const E=F=>{F.then(G=>{y(G)},G=>{let H;H=G&&(G instanceof Error||"string"==typeof G.message)?G.message:"An unexpected error occurred",y({__mozWebExtensionPolyfillReject__:!0,message:H})}).catch(G=>{console.error("Failed to send onMessage rejected reply",G)})};return D?E(C):E(B),!0}:u}),q=({reject:u,resolve:v},w)=>{chrome.runtime.lastError?chrome.runtime.lastError.message==="The message port closed before a response was received."?v():u(chrome.runtime.lastError):w&&w.__mozWebExtensionPolyfillReject__?u(new Error(w.message)):v(w)},r=(u,v,w,...x)=>{if(x.length<v.minArgs)throw new Error(`Expected at least ${v.minArgs} ${i(v.minArgs)} for ${u}(), got ${x.length}`);if(x.length>v.maxArgs)throw new Error(`Expected at most ${v.maxArgs} ${i(v.maxArgs)} for ${u}(), got ${x.length}`);return new Promise((y,z)=>{const A=q.bind(null,{resolve:y,reject:z});x.push(A),w.sendMessage(...x)})},s={runtime:{onMessage:n(p),onMessageExternal:n(p),sendMessage:r.bind(null,"sendMessage",{minArgs:1,maxArgs:3})},tabs:{sendMessage:r.bind(null,"sendMessage",{minArgs:2,maxArgs:3})}},t={clear:{minArgs:1,maxArgs:1},get:{minArgs:1,maxArgs:1},set:{minArgs:1,maxArgs:1}};return e.privacy={network:{networkPredictionEnabled:t,webRTCIPHandlingPolicy:t},services:{passwordSavingEnabled:t},websites:{hyperlinkAuditingEnabled:t,referrersEnabled:t}},m(chrome,s,e)})()}else a.exports=browser});
+//# sourceMappingURL=browser-polyfill.min.js.map
+
+
+// webextension-polyfill v.0.3.1 (https://github.com/mozilla/webextension-polyfill)
+
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
\ No newline at end of file
diff --git a/manifest.json b/manifest.json
index a561d1c..b328ee7 100644
--- a/manifest.json
+++ b/manifest.json
@@ -1,7 +1,7 @@
 {
     "manifest_version": 2,
     "name": "Beautify Practical Common Lisp",
-    "version": "1.5",
+    "version": "1.5.1",
 
     "description": "Adds a simple table of contents and syntax highlighting to the web version of Practical Common Lisp by Peter Seibel.",
 
@@ -12,6 +12,7 @@
 
     "background": {
 	"scripts": [
+	    "./js/webpoly.js",
 	    "./js/background.js"
 	]
     },
@@ -19,7 +20,7 @@
     "content_scripts": [
 	{
 	    "matches": ["*://*.gigamonkeys.com/book/*.html"],
-	    "js": ["./js/highlight-lisp.js", "./js/tocbot.js","./js/tippy.js","./js/main.js"],
+	    "js": ["./js/webpoly.js", "./js/highlight-lisp.js", "./js/tocbot.js","./js/tippy.js","./js/main.js"],
 	    "css": ["./css/highlight-style.css"]
 	}
     ],