diff --git a/lib/collection.js b/lib/collection.js
index e90916f..6bafbba 100644
--- a/lib/collection.js
+++ b/lib/collection.js
@@ -255,6 +255,10 @@ Collection.prototype.aggregate = function() {
     cb = once(pipeline.pop());
   }
 
+  if (pipeline.length === 1 && Array.isArray(pipeline[0])) {
+    pipeline = pipeline[0];
+  }
+
   if (cb) {
     this.runCommand('aggregate', {pipeline: pipeline}, function(err, res) {
       if (err) return cb(err);
diff --git a/test/test-aggregate-pipeline.js b/test/test-aggregate-pipeline.js
new file mode 100644
index 0000000..9a7ca80
--- /dev/null
+++ b/test/test-aggregate-pipeline.js
@@ -0,0 +1,41 @@
+var insert = require('./insert');
+var concat = require('concat-stream');
+
+insert('aggregate', [{
+  name:'Squirtle', type:'water'
+}, {
+  name:'Starmie' , type:'water'
+}, {
+  name:'Charmander' , type:'fire'
+}, {
+  name:'Lapras'  , type:'water'
+}], function(db, t, done) {
+  db.a.aggregate([{$group: {_id: '$type'}}, {$project: { _id: 0, foo: "$_id" }}], function(err, types) {
+    console.log(err, types);
+    var arr = types.map(function(x) {return x.foo});
+    console.log('arr', arr);
+    t.equal(types.length, 2);
+    console.log('here');
+    t.notEqual(arr.indexOf('fire'), -1);
+    console.log('there');
+    t.notEqual(arr.indexOf('water'), -1);
+    console.log('where');
+
+    // test as a stream
+    var strm = db.a.aggregate([{$group: {_id: '$type'}}, {$project: {_id: 0, foo: "$_id"}}])
+    strm.pipe(concat(function(types) {
+      var arr = types.map(function(x) {return x.foo});
+      t.equal(types.length, 2);
+      t.notEqual(arr.indexOf('fire'), -1);
+      t.notEqual(arr.indexOf('water'), -1);
+      t.end();
+    }));
+    strm.on('error', function(err) {
+      // Aggregation cursors are only supported on mongodb 2.6+
+      // this shouldn't fail the tests for other versions of mongodb
+      if (err.message === 'unrecognized field "cursor') t.ok(1);
+      else t.fail(err);
+      t.end();
+    });
+  });
+});