diff --git a/lib/stringify.js b/lib/stringify.js
index 3bdd4e93..2666eaf9 100644
--- a/lib/stringify.js
+++ b/lib/stringify.js
@@ -162,7 +162,7 @@ var stringify = function stringify(
 
     for (var j = 0; j < objKeys.length; ++j) {
         var key = objKeys[j];
-        var value = typeof key === 'object' && typeof key.value !== 'undefined'
+        var value = typeof key === 'object' && key && typeof key.value !== 'undefined'
             ? key.value
             : obj[key];
 
diff --git a/test/stringify.js b/test/stringify.js
index be9186d6..75eaf738 100644
--- a/test/stringify.js
+++ b/test/stringify.js
@@ -1298,7 +1298,7 @@ test('stringifies empty keys', function (t) {
 
     t.test('stringifies non-string keys', function (st) {
         var actual = qs.stringify({ a: 'b', 'false': {} }, {
-            filter: ['a', false],
+            filter: ['a', false, null],
             allowDots: true,
             encodeDotInKeys: true
         });