diff --git a/source/Ox.js b/source/Ox.js
index 5208dd15..242bb59c 100644
--- a/source/Ox.js
+++ b/source/Ox.js
@@ -243,11 +243,13 @@ Ox.sort = function(arr, fn) {
 Ox.unique <f> Returns an array without duplicate values
     > Ox.unique([1, 2, 3, 2, 1])
     [1, 2, 3]
+    > Ox.unique([NaN, NaN])
+    []
 @*/
 
 Ox.unique = function(arr) {
-    return Ox.map(arr, function(val) {
-        return arr.indexOf(val) == arr.lastIndexOf(val) ? val : false;
+    return Ox.map(arr, function(val, i) {
+        return arr.indexOf(val) == i ? val : null;
     });
 };
 
@@ -3902,7 +3904,7 @@ Ox.serialize <f> Parses an object into query parameters
     > Ox.serialize({a: 1, b: 2, c: 3})
     'a=1&b=2&c=3'
     > Ox.serialize({a: 1, b: 2.3, c: [4, 5]})
-    'a=1&b=2.3&c=3,4,5'
+    'a=1&b=2.3&c=4,5'
 @*/
 Ox.serialize = function(obj) {
     var arr = [];