diff --git a/lib/application.js b/lib/application.js
index 6f6cb682..ea104960 100644
--- a/lib/application.js
+++ b/lib/application.js
@@ -328,8 +328,10 @@ app.enableAuth = function(options) {
           g.f('Authentication requires model %s to be defined.', m));
       }
 
-      if (m.dataSource || m.app) return;
+      if (Model.dataSource || Model.app) return;
 
+      // Find descendants of Model that are attached,
+      // for example "Customer" extending "User" model
       for (var name in appModels) {
         var candidate = appModels[name];
         var isSubclass = candidate.prototype instanceof Model;
diff --git a/test/user.test.js b/test/user.test.js
index 0ac361bf..c638f41b 100644
--- a/test/user.test.js
+++ b/test/user.test.js
@@ -66,7 +66,6 @@ describe('User', function() {
     app.enableAuth({ dataSource: 'db' });
     app.use(loopback.token({ model: AccessToken }));
     app.use(loopback.rest());
-    app.model(User);
 
     User.create(validCredentials, function(err, user) {
       if (err) return done(err);