diff --git a/README.md b/README.md
index d8de14aa0..2e2f9e49f 100644
--- a/README.md
+++ b/README.md
@@ -1,4 +1,4 @@
-# lodash v3.9.2
+# lodash v3.9.3
 
 The [modern build](https://github.com/lodash/lodash/wiki/Build-Differences) of [lodash](https://lodash.com/) exported as [AMD](https://github.com/amdjs/amdjs-api/wiki/AMD) modules.
 
@@ -13,8 +13,8 @@ $ lodash modern exports=amd -d -o ./main.js
 Using bower or volo:
 
 ```bash
-$ bower i lodash#3.9.2-amd
-$ volo add lodash/3.9.2-amd
+$ bower i lodash#3.9.3-amd
+$ volo add lodash/3.9.3-amd
 ```
 
 Defining a build as `'lodash'`.
diff --git a/internal/isIndex.js b/internal/isIndex.js
index 92d7c6d2b..ced084b82 100644
--- a/internal/isIndex.js
+++ b/internal/isIndex.js
@@ -1,5 +1,8 @@
 define([], function() {
 
+  /** Used to detect unsigned integer values. */
+  var reIsUint = /^\d+$/;
+
   /**
    * Used as the [maximum length](https://people.mozilla.org/~jorendorff/es6-draft.html#sec-number.max_safe_integer)
    * of an array-like value.
@@ -15,7 +18,7 @@ define([], function() {
    * @returns {boolean} Returns `true` if `value` is a valid index, else `false`.
    */
   function isIndex(value, length) {
-    value = typeof value == 'number' ? value : parseFloat(value);
+    value = (typeof value == 'number' || reIsUint.test(value)) ? +value : -1;
     length = length == null ? MAX_SAFE_INTEGER : length;
     return value > -1 && value % 1 == 0 && value < length;
   }
diff --git a/main.js b/main.js
index d853f924e..84ca1b510 100644
--- a/main.js
+++ b/main.js
@@ -1,6 +1,6 @@
 /**
  * @license
- * lodash 3.9.2 (Custom Build) <https://lodash.com/>
+ * lodash 3.9.3 (Custom Build) <https://lodash.com/>
  * Build: `lodash modern exports="amd" -d -o ./main.js`
  * Copyright 2012-2015 The Dojo Foundation <http://dojofoundation.org/>
  * Based on Underscore.js 1.8.3 <http://underscorejs.org/LICENSE>
@@ -13,7 +13,7 @@
   var undefined;
 
   /** Used as the semantic version number. */
-  var VERSION = '3.9.2';
+  var VERSION = '3.9.3';
 
   /** Used to compose bitmasks for wrapper metadata. */
   var BIND_FLAG = 1,
@@ -118,6 +118,9 @@
   /** Used to detect host constructors (Safari > 5). */
   var reIsHostCtor = /^\[object .+?Constructor\]$/;
 
+  /** Used to detect unsigned integer values. */
+  var reIsUint = /^\d+$/;
+
   /** Used to match latin-1 supplementary letters (excluding mathematical operators). */
   var reLatin1 = /[\xc0-\xd6\xd8-\xde\xdf-\xf6\xf8-\xff]/g;
 
@@ -152,9 +155,8 @@
     'Array', 'ArrayBuffer', 'Date', 'Error', 'Float32Array', 'Float64Array',
     'Function', 'Int8Array', 'Int16Array', 'Int32Array', 'Math', 'Number',
     'Object', 'RegExp', 'Set', 'String', '_', 'clearTimeout', 'document',
-    'isFinite', 'parseInt', 'setTimeout', 'TypeError', 'Uint8Array',
-    'Uint8ClampedArray', 'Uint16Array', 'Uint32Array', 'WeakMap',
-    'window'
+    'isFinite', 'parseFloat', 'parseInt', 'setTimeout', 'TypeError', 'Uint8Array',
+    'Uint8ClampedArray', 'Uint16Array', 'Uint32Array', 'WeakMap', 'window'
   ];
 
   /** Used to make template sourceURLs easier to identify. */
@@ -742,6 +744,7 @@
         clearTimeout = context.clearTimeout,
         floor = Math.floor,
         getPrototypeOf = getNative(Object, 'getPrototypeOf'),
+        parseFloat = context.parseFloat,
         push = arrayProto.push,
         Set = getNative(context, 'Set'),
         setTimeout = context.setTimeout,
@@ -4069,7 +4072,7 @@
      * @returns {boolean} Returns `true` if `value` is a valid index, else `false`.
      */
     function isIndex(value, length) {
-      value = typeof value == 'number' ? value : parseFloat(value);
+      value = (typeof value == 'number' || reIsUint.test(value)) ? +value : -1;
       length = length == null ? MAX_SAFE_INTEGER : length;
       return value > -1 && value % 1 == 0 && value < length;
     }
diff --git a/package.json b/package.json
index 310f52e3f..2765c7dca 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "lodash",
-  "version": "3.9.2",
+  "version": "3.9.3",
   "main": "main.js",
   "private": true,
   "volo": {