diff --git a/chrome/content/vimperator/commands.js b/chrome/content/vimperator/commands.js
index 742699bc..9c6b3b83 100644
--- a/chrome/content/vimperator/commands.js
+++ b/chrome/content/vimperator/commands.js
@@ -1347,7 +1347,7 @@ function zoom_to(value)
         value = 100;
 
     // convert to int, if string was given
-    if (typeof(value) != "number")
+    if (typeof value != "number")
     {
         oldval = value;
         value = parseInt(oldval, 10);
diff --git a/chrome/content/vimperator/options.js b/chrome/content/vimperator/options.js
index 40f47334..76620e54 100644
--- a/chrome/content/vimperator/options.js
+++ b/chrome/content/vimperator/options.js
@@ -413,11 +413,11 @@ function get_pref(name, forced_default)
 
     try
     {
-        if (typeof(default_value) == "string")
+        if (typeof default_value == "string")
             pref = g_vimperator_prefs.getCharPref(name);
-        else if (typeof(default_value) == "number")
+        else if (typeof default_value == "number")
             pref = g_vimperator_prefs.getIntPref(name);
-        else if (typeof(default_value) == "boolean")
+        else if (typeof default_value == "boolean")
             pref = g_vimperator_prefs.getBoolPref(name);
         else
             pref = default_value;
@@ -436,11 +436,11 @@ function get_firefox_pref(name, default_value)
     var pref;
     try
     {
-        if (typeof(default_value) == "string")
+        if (typeof default_value == "string")
             pref = g_firefox_prefs.getCharPref(name);
-        else if (typeof(default_value) == "number")
+        else if (typeof default_value == "number")
             pref = g_firefox_prefs.getIntPref(name);
-        else if (typeof(default_value) == "boolean")
+        else if (typeof default_value == "boolean")
             pref = g_firefox_prefs.getBoolPref(name);
         else
             pref = default_value;
@@ -460,28 +460,28 @@ function set_pref(name, value)
     if (!g_vimperator_prefs)
         g_vimperator_prefs = g_firefox_prefs.getBranch("extensions.vimperator.");
 
-    if (typeof(value) == "string")
+    if (typeof value == "string")
         g_vimperator_prefs.setCharPref(name, value);
-    else if (typeof(value) == "number")
+    else if (typeof value == "number")
         g_vimperator_prefs.setIntPref(name, value);
-    else if (typeof(value) == "boolean")
+    else if (typeof value == "boolean")
         g_vimperator_prefs.setBoolPref(name, value);
     else
-        vimperator.echoerr("Unkown typeof pref: " + value);
+        vimperator.echoerr("Unknown typeof pref: " + value);
 }
 
 function set_firefox_pref(name, value)
 {
     // NOTE: firefox prefs are always inititialized, no need to re-init
 
-    if (typeof(value) == "string")
+    if (typeof value == "string")
         g_firefox_prefs.setCharPref(name, value);
-    else if (typeof(value) == "number")
+    else if (typeof value == "number")
         g_firefox_prefs.setIntPref(name, value);
-    else if (typeof(value) == "boolean")
+    else if (typeof value == "boolean")
         g_firefox_prefs.setBoolPref(name, value);
     else
-        vimperator.echoerr("Unkown typeof pref: " + value);
+        vimperator.echoerr("Unknown typeof pref: " + value);
 }
 
 
@@ -524,7 +524,7 @@ function set_showtabline(value)
 
 function set_titlestring(value)
 {
-    if (!value || typeof(value) != "string")
+    if (!value || typeof value != "string")
         value = get_pref("titlestring");
 
 	document.getElementById("main-window").setAttribute("titlemodifier", value);
diff --git a/chrome/content/vimperator/ui.js b/chrome/content/vimperator/ui.js
index 436b76bf..68ca82e0 100644
--- a/chrome/content/vimperator/ui.js
+++ b/chrome/content/vimperator/ui.js
@@ -110,7 +110,7 @@ function CommandLine ()
     // Sets the prompt - for example, : or /
     function setPrompt(prompt)
     {
-        if (typeof(prompt) != "string")
+        if (typeof prompt != "string")
             prompt = "";
 
         prompt_widget.value = prompt;
@@ -738,7 +738,7 @@ function StatusLine()
 
     this.updateUrl = function(url)
     {
-        if (!url || typeof(url) != "string")
+        if (!url || typeof url != "string")
             url = getCurrentLocation();
 
         url_widget.value = url;
@@ -746,7 +746,7 @@ function StatusLine()
 
     this.updateInputBuffer = function(buffer)
     {
-        if (!buffer || typeof(buffer) != "string")
+        if (!buffer || typeof buffer != "string")
             buffer = "";
 
         inputbuffer_widget.value = buffer;
@@ -757,9 +757,9 @@ function StatusLine()
         if (!progress)
             progress = "";
 
-        if (typeof(progress) == "string")
+        if (typeof progress == "string")
             progress_widget.value = progress;
-        else if (typeof(progress) == "number")
+        else if (typeof progress == "number")
         {
             var progress_str = "";
             if (progress <= 0)
@@ -785,9 +785,9 @@ function StatusLine()
     // you can omit either of the 2 arguments
     this.updateTabCount = function(cur_index, total_tabs)
     {
-        if(!cur_index || typeof(cur_index != "number"))
+        if(!cur_index || typeof cur_index != "number")
             cur_index = vimperator.tabs.index() + 1;
-        if(!total_tabs || typeof(cur_index != "number"))
+        if(!total_tabs || typeof cur_index != "number")
             total_tabs = vimperator.tabs.count();
 
         tabcount_widget.value = "[" + cur_index.toString() + "/" + total_tabs.toString() + "]";
@@ -796,7 +796,7 @@ function StatusLine()
     // percent is given between 0 and 1
     this.updateBufferPosition = function(percent)
     {
-        if(!percent || typeof(percent) != "number")
+        if(!percent || typeof percent != "number")
         {
             var win = document.commandDispatcher.focusedWindow;
             percent = win.scrollMaxY == 0 ? -1 : win.scrollY / win.scrollMaxY;
diff --git a/chrome/content/vimperator/vimperator.js b/chrome/content/vimperator/vimperator.js
index 84feb78c..ce6e88fd 100644
--- a/chrome/content/vimperator/vimperator.js
+++ b/chrome/content/vimperator/vimperator.js
@@ -246,7 +246,7 @@ function Vimperator() //{{{1
             mode = main;
             extended_mode = this.modes.NONE;
         }
-        if (typeof(extended) === "number")
+        if (typeof extended === "number")
             extended_mode = extended;
 
         if (!silent)
@@ -742,7 +742,7 @@ function Tabs() //{{{1
         if (spec === undefined || spec === "")
             return position;
 
-        if (typeof(spec) === "number")
+        if (typeof spec === "number")
             position = spec;
         else if (spec === "$")
             return last;