diff --git a/content/addressbook.js b/content/addressbook.js
index 3b104b26..c653f554 100644
--- a/content/addressbook.js
+++ b/content/addressbook.js
@@ -71,7 +71,7 @@ function Addressbook() //{{{
     ////////////////////// MAPPINGS ////////////////////////////////////////////////
     /////////////////////////////////////////////////////////////////////////////{{{
 
-    var myModes = config.mailModes || [modes.NORMAL];
+    var myModes = config.mailModes;
 
     mappings.add(myModes, ["a"],
         "Open a prompt to save a new addressbook entry for the sender of the selected message",
diff --git a/content/bookmarks.js b/content/bookmarks.js
index cd49eb92..b41cb6b7 100644
--- a/content/bookmarks.js
+++ b/content/bookmarks.js
@@ -240,7 +240,7 @@ function Bookmarks() //{{{
     ////////////////////// MAPPINGS ////////////////////////////////////////////////
     /////////////////////////////////////////////////////////////////////////////{{{
 
-    var myModes = config.browserModes || [modes.NORMAL];
+    var myModes = config.browserModes;
 
     mappings.add(myModes, ["a"],
         "Open a prompt to bookmark the current URL",
@@ -595,7 +595,7 @@ function History() //{{{
     ////////////////////// MAPPINGS ////////////////////////////////////////////////
     /////////////////////////////////////////////////////////////////////////////{{{
 
-    var myModes = config.browserModes || [modes.NORMAL];
+    var myModes = config.browserModes;
 
     mappings.add(myModes,
         ["<C-o>"], "Go to an older position in the jump list",
@@ -855,7 +855,7 @@ function QuickMarks() //{{{
     ////////////////////// MAPPINGS ////////////////////////////////////////////////
     /////////////////////////////////////////////////////////////////////////////{{{
 
-    var myModes = config.browserModes || [modes.NORMAL];
+    var myModes = config.browserModes;
 
     mappings.add(myModes,
         ["go"], "Jump to a QuickMark",
diff --git a/content/buffer.js b/content/buffer.js
index 13171c7d..dc762be0 100644
--- a/content/buffer.js
+++ b/content/buffer.js
@@ -193,7 +193,7 @@ function Buffer() //{{{
     ////////////////////// MAPPINGS ////////////////////////////////////////////////
     /////////////////////////////////////////////////////////////////////////////{{{
 
-    var myModes = config.browserModes || [modes.NORMAL];
+    var myModes = config.browserModes;
 
     mappings.add(myModes, ["."],
         "Repeat the last key event",
@@ -1454,7 +1454,7 @@ function Marks() //{{{
     ////////////////////// MAPPINGS ////////////////////////////////////////////////
     /////////////////////////////////////////////////////////////////////////////{{{
 
-    var myModes = config.browserModes || [modes.NORMAL];
+    var myModes = config.browserModes;
 
     mappings.add(myModes,
         ["m"], "Set mark at the cursor position",
diff --git a/content/completion.js b/content/completion.js
index c400ca43..fe03b5ab 100644
--- a/content/completion.js
+++ b/content/completion.js
@@ -867,7 +867,7 @@ function Completion() //{{{
             return [0, buildLongestStartingSubstring(completions, filter)];
         },
 
-        dialog: function dialog(filter) [0, this.filter(config.dialogs || [], filter)],
+        dialog: function dialog(filter) [0, this.filter(config.dialogs, filter)],
 
         environment: function environment(filter)
         {
@@ -970,7 +970,7 @@ function Completion() //{{{
 
         help: function help(filter)
         {
-            var files = config.helpFiles || [];
+            var files = config.helpFiles;
             var res = [];
 
             for (let i = 0; i < files.length; i++)
diff --git a/content/find.js b/content/find.js
index f2264bb3..7b2eb11a 100644
--- a/content/find.js
+++ b/content/find.js
@@ -390,7 +390,7 @@ function Search() //{{{
     ////////////////////// MAPPINGS ////////////////////////////////////////////////
     /////////////////////////////////////////////////////////////////////////////{{{
 
-    var myModes = config.browserModes || [modes.NORMAL];
+    var myModes = config.browserModes;
     myModes = myModes.concat([modes.CARET]);
 
     mappings.add(myModes,
diff --git a/content/hints.js b/content/hints.js
index 90674075..77e52229 100644
--- a/content/hints.js
+++ b/content/hints.js
@@ -32,7 +32,7 @@ function Hints() //{{{
     ////////////////////// PRIVATE SECTION /////////////////////////////////////////
     /////////////////////////////////////////////////////////////////////////////{{{
 
-    var myModes = config.browserModes || [modes.NORMAL];
+    var myModes = config.browserModes;
 
     var hintMode;
     var submode    = ""; // used for extended mode, can be "o", "t", "y", etc.
diff --git a/content/liberator-overlay.js b/content/liberator-overlay.js
index 2ff583aa..d2c8bbe0 100644
--- a/content/liberator-overlay.js
+++ b/content/liberator-overlay.js
@@ -40,7 +40,9 @@
      "options.js",
      "template.js",
      "ui.js"].forEach(load);
-    modules.config.scripts.forEach(load);
+
+    if (modules.config.scripts)
+        modules.config.scripts.forEach(load);
 
 })()
 
diff --git a/content/liberator.js b/content/liberator.js
index bd39828b..511a5d1d 100644
--- a/content/liberator.js
+++ b/content/liberator.js
@@ -82,7 +82,7 @@ const liberator = (function () //{{{
             {
                 setter: function (value)
                 {
-                    for (let [opt, ids] in Iterator(config.guioptions || {}))
+                    for (let [opt, ids] in Iterator(config.guioptions))
                     {
                         ids.forEach(function (id)
                         {
@@ -186,7 +186,7 @@ const liberator = (function () //{{{
 
                 try
                 {
-                    var dialogs = config.dialogs || [];
+                    var dialogs = config.dialogs;
                     for (let i = 0; i < dialogs.length; i++)
                     {
                         if (dialogs[i][0] == args)
@@ -536,7 +536,7 @@ const liberator = (function () //{{{
     // similar in his config
     function hideGUI()
     {
-        var guioptions = config.guioptions || {};
+        var guioptions = config.guioptions;
         for (let option in guioptions)
         {
             guioptions[option].forEach(function (elem) {
@@ -864,12 +864,8 @@ const liberator = (function () //{{{
                 commandline.echo(str, commandline.HL_INFOMSG, flags);
         },
 
-        // return true, if this liberator extension has a certain feature
-        has: function (feature)
-        {
-            let features = config.features || [];
-            return features.indexOf(feature) >= 0;
-        },
+        // does this liberator extension have a certain feature?
+        has: function (feature) config.features.indexOf(feature) >= 0,
 
         hasExtension: function (name)
         {
@@ -1146,9 +1142,20 @@ const liberator = (function () //{{{
             let start = Date.now();
             liberator.log("Initializing liberator object...", 0);
 
-            // TODO: only checked for "Win32" currently, other values should be normalised
-
+            config.features = config.features || [];
             config.features.push(getPlatformFeature());
+            config.defaults = config.defaults || {};
+            config.guioptions = config.guioptions || {};
+            config.browserModes = config.browserModes || [modes.NORMAL];
+            config.mailModes = config.mailModes || [modes.NORMAL];
+            // TODO: suitable defaults?
+            //config.mainWidget
+            //config.mainWindowID
+            //config.visualbellWindow
+            //config.styleableChrome
+            config.autocommands = config.autocommands || [];
+            config.dialogs = config.dialogs || [];
+            config.helpFiles = config.helpFiles || [];
 
             // commands must always be the first module to be initialized
             loadModule("commands",     Commands);
diff --git a/content/mail.js b/content/mail.js
index 63985e10..a6f8d182 100644
--- a/content/mail.js
+++ b/content/mail.js
@@ -241,7 +241,7 @@ function Mail() //{{{
     ////////////////////// MAPPINGS ////////////////////////////////////////////////
     /////////////////////////////////////////////////////////////////////////////{{{
 
-    var myModes = config.mailModes || [modes.NORMAL];
+    var myModes = config.mailModes;
 
     mappings.add(myModes, ["<Return>", "i"],
         "Inspect (focus) message",