diff --git a/lib/stringify.js b/lib/stringify.js
index 4015b785..d3130bd8 100644
--- a/lib/stringify.js
+++ b/lib/stringify.js
@@ -15,6 +15,14 @@ var arrayPrefixGenerators = {
     }
 };
 
+var pushToArray = function (arr, valueOrArray) {
+    if (Array.isArray(valueOrArray)) {
+        Array.prototype.push.apply(arr, valueOrArray);
+    } else {
+        arr.push(valueOrArray);
+    }
+};
+
 var toISO = Date.prototype.toISOString;
 
 var defaults = {
@@ -93,7 +101,7 @@ var stringify = function stringify( // eslint-disable-line func-name-matching
         }
 
         if (Array.isArray(obj)) {
-            values = values.concat(stringify(
+            pushToArray(values, stringify(
                 obj[key],
                 generateArrayPrefix(prefix, key),
                 generateArrayPrefix,
@@ -109,7 +117,7 @@ var stringify = function stringify( // eslint-disable-line func-name-matching
                 charset
             ));
         } else {
-            values = values.concat(stringify(
+            pushToArray(values, stringify(
                 obj[key],
                 prefix + (allowDots ? '.' + key : '[' + key + ']'),
                 generateArrayPrefix,
@@ -200,8 +208,7 @@ module.exports = function (object, opts) {
         if (skipNulls && obj[key] === null) {
             continue;
         }
-
-        keys = keys.concat(stringify(
+        pushToArray(keys, stringify(
             obj[key],
             key,
             generateArrayPrefix,