diff --git a/source/Ox/js/Type.js b/source/Ox/js/Type.js
index 258c7014..331ee625 100644
--- a/source/Ox/js/Type.js
+++ b/source/Ox/js/Type.js
@@ -341,31 +341,33 @@ Ox.typeOf = function(value) {
 // Internet Explorer 8 returns 'Object' instead of 'NodeList',
 // Internet Explorer 9 returns 'HTMLCollection' instead of 'NodeList',
 // Mobile Safari doesn't like null and undefined
-if (
-    Ox.typeOf(arguments) != 'arguments'
-    || Ox.typeOf(document.getElementsByTagName('a')) != 'nodelist'
-    || Ox.typeOf(null) != 'null'
-    || Ox.typeOf() != 'undefined'
-) {
-    Ox.typeOf = function(value) {
-        var ret = Object.prototype.toString.call(
-                value
-            ).slice(8, -1).toLowerCase();
-        if (typeof value.callee == 'function') {
-            ret = 'arguments';
-        } else if (
-            ret == 'htmlcollection' || (
-                ret == 'object'
-                && typeof value.item != 'undefined'
-                && typeof value.length == 'number'
-            )
-        ) {
-            ret = 'nodelist';
-        } else if (value === null) {
-            ret = 'null';
-        } else if (value === void 0) {
-            ret = 'undefined'
-        }
-        return ret;
-    };
-}
+(function() {
+    if (
+        Ox.typeOf(arguments) != 'arguments'
+        || Ox.typeOf(document.getElementsByTagName('a')) != 'nodelist'
+        || Ox.typeOf(null) != 'null'
+        || Ox.typeOf() != 'undefined'
+    ) {
+        Ox.typeOf = function(value) {
+            var ret = Object.prototype.toString.call(
+                    value
+                ).slice(8, -1).toLowerCase();
+            if (typeof value.callee == 'function') {
+                ret = 'arguments';
+            } else if (
+                ret == 'htmlcollection' || (
+                    ret == 'object'
+                    && typeof value.item != 'undefined'
+                    && typeof value.length == 'number'
+                )
+            ) {
+                ret = 'nodelist';
+            } else if (value === null) {
+                ret = 'null';
+            } else if (value === void 0) {
+                ret = 'undefined'
+            }
+            return ret;
+        };
+    }
+})();