diff --git a/lib/loopback.js b/lib/loopback.js
index d5db06df..ab0a79e2 100644
--- a/lib/loopback.js
+++ b/lib/loopback.js
@@ -243,7 +243,8 @@ loopback.autoAttach = function() {
   Object.keys(models).forEach(function(modelName) {
     var ModelCtor = models[modelName];
 
-    if(ModelCtor) {
+    // Only auto attach if the model doesn't have an explicit data source
+    if(ModelCtor && (!(ModelCtor.dataSource instanceof DataSource))) {
       loopback.autoAttachModel(ModelCtor);
     }
   });