diff --git a/lib/database.js b/lib/database.js
index b6c17f9..ad30031 100644
--- a/lib/database.js
+++ b/lib/database.js
@@ -35,6 +35,7 @@ var Document = require("./document");
 
 // database extends backbone collection
 Database.prototype = Object.create(Backbone.Collection.prototype);
+Database.extend = Backbone.Collection.extend;
 
 // database class extends document
 _.extend(Database.prototype, {
diff --git a/test/test.js b/test/test.js
index c520381..18e9765 100644
--- a/test/test.js
+++ b/test/test.js
@@ -21,6 +21,12 @@ describe("Documents", function() {
 		expect(doc.isNew()).to.not.be.ok;
 	});
 
+	it("can create subclass from Document class", function() {
+		var subclass = Lazybones.Document.extend({ foo: function() {} });
+		expect(subclass.prototype.foo).to.be.a.function;
+		expect(subclass.prototype.get).to.be.a.function;
+	});
+
 });
 
 describe("Database", function() {
@@ -41,6 +47,12 @@ describe("Database", function() {
 		db.destroy().then(function() { done(); }, done);
 	});
 
+	it("can create subclass from Database class", function() {
+		var subclass = Lazybones.extend({ foo: function() {} });
+		expect(subclass.prototype.foo).to.be.a.function;
+		expect(subclass.prototype.get).to.be.a.function;
+	});
+
 });
 
 describe("CRUD", function() {