diff --git a/content/util.js b/content/util.js
index f095a95b..6269a758 100644
--- a/content/util.js
+++ b/content/util.js
@@ -41,40 +41,48 @@ vimperator.util = {
     {
         var type = typeof(arg);
 
-        if (type == "number")
+        // some objects like window.JSON or getBrowsers()._browsers need the try/catch
+        try
         {
-            return "<span style=\"color: red;\">" + arg + "</span>";
-        }
-        else if (type == "string")
-        {
-            if (process_strings)
-                arg = '"' + vimperator.util.escapeHTML(arg.replace(/\n/, "\\n")) + '"';
+            if (type == "number")
+            {
+                return "<span style=\"color: red;\">" + arg + "</span>";
+            }
+            else if (type == "string")
+            {
+                if (process_strings)
+                    arg = '"' + vimperator.util.escapeHTML(arg.replace(/\n/, "\\n")) + '"';
 
-            return "<span style=\"color: green;\">" + arg + "</span>";
-        }           
-        else if (type == "boolean")
-        {
-            return "<span style=\"color: blue;\">" + arg + "</span>";
-        }
-        else if (arg == null || arg == "undefined")
-        {
-            return "<span style=\"color: blue;\">" + arg + "</span>";
-        }
-        else if (type == "object" || type == "function")
-        {
-            // for java packages value.toString() would crash so badly 
-            // that we cannot even try/catch it
-            if (/^\[JavaPackage.*\]$/.test(arg)) 
-                return "[JavaPackage]";
+                return "<span style=\"color: green;\">" + arg + "</span>";
+            }           
+            else if (type == "boolean")
+            {
+                return "<span style=\"color: blue;\">" + arg + "</span>";
+            }
+            else if (arg == null || arg == "undefined")
+            {
+                return "<span style=\"color: blue;\">" + arg + "</span>";
+            }
+            else if (type == "object" || type == "function")
+            {
+                // for java packages value.toString() would crash so badly 
+                // that we cannot even try/catch it
+                if (/^\[JavaPackage.*\]$/.test(arg)) 
+                    return "[JavaPackage]";
 
-            var str = arg.toString();
-            if (typeof str == "string")  // can be "undefined"
-                return vimperator.util.escapeHTML(str);
-            else
-                return "undefined";
+                var str = arg.toString();
+                if (typeof str == "string")  // can be "undefined"
+                    return vimperator.util.escapeHTML(str);
+                else
+                    return "undefined";
+            }
+        }
+        catch (e)
+        {
+            return "&lt;unknown&gt;";
         }
 
-        return arg;
+        return "&lt;unknown type&gt;";
     }
 }
 
diff --git a/content/vimperator.js b/content/vimperator.js
index cb56a4bd..b1c817b4 100644
--- a/content/vimperator.js
+++ b/content/vimperator.js
@@ -360,29 +360,31 @@ const vimperator = (function() //{{{
             else
                 string += obj + "::\n";
 
-            for (var i in object)
+            try // window.content often does not want to be queried with "var i in object"
             {
-                var value;
-                try
+                for (var i in object)
                 {
-                    if (i == "JSON") // without this ugly hack, ":echo window" does not work
-                        value = "[object JSON]";
-                    else
+                    var value;
+                    try
+                    {
                         value = object[i];
-                }
-                catch (e)
-                {
-                    value = "";
-                }
+                    }
+                    catch (e)
+                    {
+                        value = "&lt;no value&gt;";
+                    }
 
-                if (color)
-                {
-                    value = vimperator.util.colorize(value, true);
-                    string += "<span style=\"font-weight: bold;\">" + i + "</span>: " + value + "\n";
+                    if (color)
+                    {
+                        value = vimperator.util.colorize(value, true);
+                        string += "<span style=\"font-weight: bold;\">" + i + "</span>: " + value + "\n";
+                    }
+                    else
+                        string += i + ": " + value + "\n";
                 }
-                else
-                    string += i + ": " + value + "\n";
             }
+            catch (e) { };
+
             return string;
         },