diff --git a/index.js b/index.js
index 62bd4ed..9a484b5 100644
--- a/index.js
+++ b/index.js
@@ -1,5 +1,5 @@
 wrapAsync = (Meteor.wrapAsync)? Meteor.wrapAsync : Meteor._wrapAsync;
-Mongo.Collection.prototype.aggregate = function(pipelines, options) {
+Mongo.Collection.prototype.aggregate = function(pipelines = [], options) {
   var coll;
   if (this.rawCollection) {
     // >= Meteor 1.0.4
@@ -8,5 +8,21 @@ Mongo.Collection.prototype.aggregate = function(pipelines, options) {
 	// < Meteor 1.0.4
     coll = this._getCollection();
   }
-  return wrapAsync(coll.aggregate.bind(coll))(pipelines, options);
+  if(parseInt(MongoInternals.NpmModules.mongodb.version) >= 3) {
+    const cursor = wrapAsync(coll.aggregate, coll)(pipelines, options);
+    return wrapAsync(cursor.toArray, cursor)();
+  } else {
+    return wrapAsync(coll.aggregate.bind(coll))(pipelines, options);
+  }
+}
+Mongo.Collection.prototype.mapReduce = function(mapFunction, reduceFunction, options) {
+  var coll;
+  if (this.rawCollection) {
+    // >= Meteor 1.0.4
+    coll = this.rawCollection();
+  } else {
+	// < Meteor 1.0.4
+    coll = this._getCollection();
+  }
+  return wrapAsync(coll.mapReduce.bind(coll))(mapFunction, reduceFunction, options);
 }
diff --git a/package.js b/package.js
index f923c30..46bf830 100644
--- a/package.js
+++ b/package.js
@@ -1,6 +1,6 @@
 Package.describe({
   "summary": "Proper MongoDB aggregations support for Meteor",
-  "version": "1.3.0",
+  "version": "1.4.0",
   "git": "https://github.com/meteorhacks/meteor-aggregate.git",
   "name": "meteorhacks:aggregate"
 });
@@ -12,7 +12,7 @@ Package.onUse(function(api) {
 Package.onTest(function(api) {
   configurePackage(api);
   api.use([
-    'tinytest', 'accounts-password'
+    'tinytest', 'accounts-password', 'random'
   ], ['server']);
 
   // common before
@@ -24,7 +24,7 @@ Package.onTest(function(api) {
 function configurePackage(api) {
   api.versionsFrom('METEOR@1.0');
   api.use(['mongo-livedata', 'meteorhacks:collection-utils@1.2.0'], ['server']);
-
+  
   // common before
   api.addFiles([
     'index.js',
diff --git a/test.js b/test.js
index 960122a..72febf5 100644
--- a/test.js
+++ b/test.js
@@ -39,4 +39,27 @@ Tinytest.add("using some options", function(test) {
   ], options);
 
   test.equal(typeof result[0]['$cursor'], 'object');
-});
\ No newline at end of file
+});
+
+Tinytest.add("method mapReduce signature", function(test) {
+  var coll = new Mongo.Collection(Random.id());
+  test.equal(typeof coll.mapReduce, 'function');
+});
+
+Tinytest.add("let's mapReduce", function(test) {
+  var coll = new Mongo.Collection(Random.id());
+  coll.insert({group: 1, value: 10});
+  coll.insert({group: 1, value: 100});
+  coll.insert({group: 2, value: 1000});
+
+  var mapFunction1 = function() {
+    emit(this.group, this.value);
+  };
+  var reduceFunction1 = function(keyGroupId, values) {
+    return Array.sum(values);
+  };
+
+  var result = coll.mapReduce(mapFunction1, reduceFunction1, { out: { inline: 1 } })
+
+  test.equal(result, [{"_id":1,"value":110},{"_id":2,"value":1000}]);
+});