diff --git a/content/commands.js b/content/commands.js
index 80ca8fcd..e31aedfe 100644
--- a/content/commands.js
+++ b/content/commands.js
@@ -1932,7 +1932,7 @@ vimperator.Commands = function () //{{{
                 else if (reset)
                     vimperator.options.resetFirefoxPref(name);
                 else if (invertBoolean)
-                    vimperator.options.invertFirefoxBoolean(name);
+                    vimperator.options.invertFirefoxPref(name);
                 else if (matches[3])
                 {
                     var value = matches[5];
diff --git a/content/completion.js b/content/completion.js
index c3ec11f1..8146a88f 100644
--- a/content/completion.js
+++ b/content/completion.js
@@ -391,10 +391,12 @@ vimperator.Completion = function () //{{{
                 }
 
                 for (var i = 0; i < prefArray.length; i++)
+                {
                     if (!filter)
                         optionCompletions.push([prefArray[i], vimperator.options.getFirefoxPref(prefArray[i])]);
                     else
                         optionCompletions.push([[prefArray[i]], vimperator.options.getFirefoxPref(prefArray[i])]);
+                }
                         
 
                 if (!filter)
@@ -421,7 +423,7 @@ vimperator.Completion = function () //{{{
                 for (var option in vimperator.options)
                 {
                     if (option.hasName(filter))
-                        return [filter.length + 1, [[option.value, ""]]];
+                        return [filter.length + 1, [[option.value + "", ""]]];
                 }
                 return [0, optionCompletions];
             }
diff --git a/content/options.js b/content/options.js
index 5c9959e0..82ea8b6f 100644
--- a/content/options.js
+++ b/content/options.js
@@ -447,7 +447,9 @@ vimperator.Options = function () //{{{
         {
             return firefoxBranch.clearUserPref(name);
         },
-        invertFirefoxBoolean: function (name)
+
+        // this works only for booleans
+        invertFirefoxPref: function (name)
         {
             if (firefoxBranch.getPrefType(name) == firefoxBranch.PREF_BOOL)
                 this.setFirefoxPref(name, !this.getFirefoxPref(name));