diff --git a/source/Ox/js/Type.js b/source/Ox/js/Type.js
index ce8a18d8..dcbc2b10 100644
--- a/source/Ox/js/Type.js
+++ b/source/Ox/js/Type.js
@@ -137,7 +137,7 @@ Ox.isEqual = function(a, b) {
         ret = a !== 0 || 1 / a === 1 / b;
     } else if (type == Ox.typeOf(b)) {
         // NaN !== NaN, but equal
-        if (a == b || a !== b) {
+        if (a == b || a !== a) {
             ret = true;
         } else if (type == 'date') {
             ret = +a == +b;