diff --git a/lodash.src.js b/lodash.src.js
index 06cd1926b..109a4e497 100644
--- a/lodash.src.js
+++ b/lodash.src.js
@@ -3294,6 +3294,25 @@
       return curryFunc;
     }
 
+    /**
+     * Creates a `_.defaults` or `_.defaultsDeep` function.
+     *
+     * @private
+     * @param {Function} assigner The function to assign values.
+     * @param {Function} customizer The function to customize assigned values.
+     * @returns {Function} Returns the new defaults function.
+     */
+    function createDefaults(assigner, customizer) {
+      return restParam(function(args) {
+        var object = args[0];
+        if (object == null) {
+          return object;
+        }
+        args.push(customizer);
+        return assigner.apply(undefined, args);
+      });
+    }
+
     /**
      * Creates a `_.max` or `_.min` function.
      *
@@ -4344,6 +4363,18 @@
       return data;
     }
 
+    /**
+     * Used by `_.defaultsDeep` to customize its `_.merge` use.
+     *
+     * @private
+     * @param {*} objectValue The destination object property value.
+     * @param {*} sourceValue The source object property value.
+     * @returns {*} Returns the value to assign to the destination object.
+     */
+    function mergeDefaults(objectValue, sourceValue) {
+      return objectValue === undefined ? sourceValue : merge(objectValue, sourceValue, mergeDefaults);
+    }
+
     /**
      * A specialized version of `_.pick` which picks `object` properties specified
      * by `props`.
@@ -9238,6 +9269,56 @@
 
     /*------------------------------------------------------------------------*/
 
+    /**
+     * Recursively merges own enumerable properties of the source object(s), that
+     * don't resolve to `undefined` into the destination object. Subsequent sources
+     * overwrite property assignments of previous sources. If `customizer` is
+     * provided it is invoked to produce the merged values of the destination and
+     * source properties. If `customizer` returns `undefined` merging is handled
+     * by the method instead. The `customizer` is bound to `thisArg` and invoked
+     * with five arguments: (objectValue, sourceValue, key, object, source).
+     *
+     * @static
+     * @memberOf _
+     * @category Object
+     * @param {Object} object The destination object.
+     * @param {...Object} [sources] The source objects.
+     * @param {Function} [customizer] The function to customize assigned values.
+     * @param {*} [thisArg] The `this` binding of `customizer`.
+     * @returns {Object} Returns `object`.
+     * @example
+     *
+     * var users = {
+     *   'data': [{ 'user': 'barney' }, { 'user': 'fred' }]
+     * };
+     *
+     * var ages = {
+     *   'data': [{ 'age': 36 }, { 'age': 40 }]
+     * };
+     *
+     * _.merge(users, ages);
+     * // => { 'data': [{ 'user': 'barney', 'age': 36 }, { 'user': 'fred', 'age': 40 }] }
+     *
+     * // using a customizer callback
+     * var object = {
+     *   'fruits': ['apple'],
+     *   'vegetables': ['beet']
+     * };
+     *
+     * var other = {
+     *   'fruits': ['banana'],
+     *   'vegetables': ['carrot']
+     * };
+     *
+     * _.merge(object, other, function(a, b) {
+     *   if (_.isArray(a)) {
+     *     return a.concat(b);
+     *   }
+     * });
+     * // => { 'fruits': ['apple', 'banana'], 'vegetables': ['beet', 'carrot'] }
+     */
+    var merge = createAssigner(baseMerge);
+
     /**
      * Assigns own enumerable properties of source object(s) to the destination
      * object. Subsequent sources overwrite property assignments of previous sources.
@@ -9336,14 +9417,27 @@
      * _.defaults({ 'user': 'barney' }, { 'age': 36 }, { 'user': 'fred' });
      * // => { 'user': 'barney', 'age': 36 }
      */
-    var defaults = restParam(function(args) {
-      var object = args[0];
-      if (object == null) {
-        return object;
-      }
-      args.push(assignDefaults);
-      return assign.apply(undefined, args);
-    });
+    var defaults = createDefaults(assign, assignDefaults);
+
+    /**
+     * This method is like `_.defaults` except that it recursively assigns
+     * default properties.
+     *
+     * **Note:** This method mutates `object`.
+     *
+     * @static
+     * @memberOf _
+     * @category Object
+     * @param {Object} object The destination object.
+     * @param {...Object} [sources] The source objects.
+     * @returns {Object} Returns `object`.
+     * @example
+     *
+     * _.defaultsDeep({ 'user': { 'name': 'barney' } }, { 'user': { 'name': 'fred', 'age': 36 } });
+     * // => { 'user': { 'name': 'barney', 'age': 36 } }
+     *
+     */
+    var defaultsDeep = createDefaults(merge, mergeDefaults);
 
     /**
      * This method is like `_.find` except that it returns the key of the first
@@ -9875,56 +9969,6 @@
      */
     var mapValues = createObjectMapper();
 
-    /**
-     * Recursively merges own enumerable properties of the source object(s), that
-     * don't resolve to `undefined` into the destination object. Subsequent sources
-     * overwrite property assignments of previous sources. If `customizer` is
-     * provided it is invoked to produce the merged values of the destination and
-     * source properties. If `customizer` returns `undefined` merging is handled
-     * by the method instead. The `customizer` is bound to `thisArg` and invoked
-     * with five arguments: (objectValue, sourceValue, key, object, source).
-     *
-     * @static
-     * @memberOf _
-     * @category Object
-     * @param {Object} object The destination object.
-     * @param {...Object} [sources] The source objects.
-     * @param {Function} [customizer] The function to customize assigned values.
-     * @param {*} [thisArg] The `this` binding of `customizer`.
-     * @returns {Object} Returns `object`.
-     * @example
-     *
-     * var users = {
-     *   'data': [{ 'user': 'barney' }, { 'user': 'fred' }]
-     * };
-     *
-     * var ages = {
-     *   'data': [{ 'age': 36 }, { 'age': 40 }]
-     * };
-     *
-     * _.merge(users, ages);
-     * // => { 'data': [{ 'user': 'barney', 'age': 36 }, { 'user': 'fred', 'age': 40 }] }
-     *
-     * // using a customizer callback
-     * var object = {
-     *   'fruits': ['apple'],
-     *   'vegetables': ['beet']
-     * };
-     *
-     * var other = {
-     *   'fruits': ['banana'],
-     *   'vegetables': ['carrot']
-     * };
-     *
-     * _.merge(object, other, function(a, b) {
-     *   if (_.isArray(a)) {
-     *     return a.concat(b);
-     *   }
-     * });
-     * // => { 'fruits': ['apple', 'banana'], 'vegetables': ['beet', 'carrot'] }
-     */
-    var merge = createAssigner(baseMerge);
-
     /**
      * The opposite of `_.pick`; this method creates an object composed of the
      * own and inherited enumerable properties of `object` that are not omitted.
@@ -11991,6 +12035,7 @@
     lodash.curryRight = curryRight;
     lodash.debounce = debounce;
     lodash.defaults = defaults;
+    lodash.defaultsDeep = defaultsDeep;
     lodash.defer = defer;
     lodash.delay = delay;
     lodash.difference = difference;
diff --git a/test/test.js b/test/test.js
index f861695dd..a06fabc2b 100644
--- a/test/test.js
+++ b/test/test.js
@@ -17949,7 +17949,7 @@
 
     var acceptFalsey = _.difference(allMethods, rejectFalsey);
 
-    test('should accept falsey arguments', 228, function() {
+    test('should accept falsey arguments', 229, function() {
       var emptyArrays = _.map(falsey, _.constant([])),
           isExposed = '_' in root,
           oldDash = root._;