diff --git a/index.js b/index.js
index c769b0c..d3a21ae 100644
--- a/index.js
+++ b/index.js
@@ -493,9 +493,10 @@ var isMongojsDb = function(db) {
 };
 
 var connect = function(config, collections) {
-  if (isMongojsDb(config)) return config;
   if (isDriverDb(config)) {
     var driverDb = config;
+  } else if (isMongojsDb(config)) {
+    var mongojsDb = config;
   } else {
     var connectionString = parseConfig(config);
     var dbName = (connectionString.match(/\/([^\/\?]+)(\?|$)/) || [])[1] || 'db';
@@ -519,6 +520,14 @@ var connect = function(config, collections) {
       callback(null, driverDb);
     };
   }
+  if (mongojsDb) {
+    ondb = function(callback) {
+      mongojsDb.open(function(err, db) {
+        if (err) callback(err);
+        callback(null, db);
+      });
+    }
+  }
   var that = new Database(dbName, ondb);
 
   that.bson = mongodb.BSONPure; // backwards compat (require('bson') instead)
diff --git a/package.json b/package.json
index 4febdff..a927152 100644
--- a/package.json
+++ b/package.json
@@ -33,6 +33,7 @@
     "test": "tape test/test-*.js; echo \"Harmony tests\"; node --harmony node_modules/tape/bin/tape test/test-*.js"
   },
   "devDependencies": {
+    "each-series": "^0.2.0",
     "tape": "^2.13.4"
   }
 }
diff --git a/test/test-pass-driver-db.js b/test/test-pass-driver-db.js
index 2b7a9e7..7d97245 100644
--- a/test/test-pass-driver-db.js
+++ b/test/test-pass-driver-db.js
@@ -1,33 +1,39 @@
 var test = require('tape');
 var mongodb = require('mongodb');
 var mongojs = require('../');
+var each = require('each-series');
 
-test('receive a driver db instance', function(t) {
+test('receive a driver db or mongojs instance', function(t) {
   mongodb.Db.connect('mongodb://localhost/test', function(err, thedb) {
-    var db = mongojs(thedb, ['a']);
 
-    var afterFind = function() {
-      db.a.remove(function(err) {
-        t.ok(!err);
-        t.equal(db.toString(), 'test');
-        t.end();
-      });
-    };
+    var doTests = function(db, callback) {
+      var afterFind = function() {
+        db.a.remove(function(err) {
+          t.ok(!err);
+          t.equal(db.toString(), 'test');
+          callback();
+        });
+      };
 
-    var afterInsert = function(err) {
-      t.ok(!err);
+      var afterInsert = function(err) {
+        t.ok(!err);
 
-      db.a.findOne(function(err, data) {
-        t.equal(data.name, 'Pidgey');
-        afterFind();
-      });
-    };
+        db.a.findOne(function(err, data) {
+          t.equal(data.name, 'Pidgey');
+          afterFind();
+        });
+      };
 
-    var afterRemove = function(err) {
-      t.ok(!err);
-      db.a.insert({name: 'Pidgey'}, afterInsert);
+      var afterRemove = function(err) {
+        t.ok(!err);
+        db.a.insert({name: 'Pidgey'}, afterInsert);
 
+      };
+      db.a.remove(afterRemove);
     };
-    db.a.remove(afterRemove);
+
+    each([mongojs(thedb, ['a']), mongojs(mongojs('test', []), ['a'])], function(db, i, cb) {
+      doTests(db, cb);
+    }, t.end.bind(t));
   });
 });
diff --git a/test/test-pass-mongojs-db.js b/test/test-pass-mongojs-db.js
deleted file mode 100644
index 868a1f0..0000000
--- a/test/test-pass-mongojs-db.js
+++ /dev/null
@@ -1,9 +0,0 @@
-var test = require('tape');
-var mongojs = require('../');
-var db = mongojs('test');
-
-test('receive a driver db instance', function(t) {
-  var thedb = mongojs(db);
-  t.ok(db === thedb);
-  t.end();
-});