diff --git a/extension/chrome/content/nightly.js b/extension/chrome/content/nightly.js
index 2428a87..b880c6f 100644
--- a/extension/chrome/content/nightly.js
+++ b/extension/chrome/content/nightly.js
@@ -142,7 +142,16 @@ getStoredItem: function(type, name) {
     return nightly.preferences.getCharPref(type+"."+name);
   }
   catch (e) {}
-  return nightly[type][name];
+
+  if (nightly[type].hasOwnProperty(name)) {
+    varvalue = nightly[type][name];
+    if (varvalue === undefined || varvalue === null) {
+      varvalue = nightly.getString("nightly.variables.nullvalue");
+    }
+    return varvalue;
+  }
+
+  return undefined;
 },
 
 getVariable: function(name) {
diff --git a/extension/chrome/content/titlebar/customize.js b/extension/chrome/content/titlebar/customize.js
index 4318530..7310eb5 100644
--- a/extension/chrome/content/titlebar/customize.js
+++ b/extension/chrome/content/titlebar/customize.js
@@ -118,10 +118,6 @@ addVariable: function(name)
     text="";
   }
   var value = paneTitle.nightly.getVariable(name);
-  if (value==null)
-  {
-    value="Undefined";
-  }
   paneTitle.variables.push({variable: "${"+name+"}", description: text, value: value});
 },
 
diff --git a/extension/chrome/locale/en-US/nightly.properties b/extension/chrome/locale/en-US/nightly.properties
index d07c3c8..8a6c11a 100644
--- a/extension/chrome/locale/en-US/nightly.properties
+++ b/extension/chrome/locale/en-US/nightly.properties
@@ -8,3 +8,4 @@ nightly.noextensions.message=No extensions were found.
 nightly.restart.message=Addon compatibility has changed, restart to affect currently installed addons
 nightly.restart.label=Restart
 nightly.restart.accesskey=R
+nightly.variables.nullvalue=Undefined