diff --git a/lib/abstract-class.js b/lib/abstract-class.js
index 453794b7..8167359c 100644
--- a/lib/abstract-class.js
+++ b/lib/abstract-class.js
@@ -440,6 +440,8 @@ AbstractClass.include = function (objects, include, cb) {
                     cb(null, objects);
                 }
             });
+        } else {
+            cb(null, objects);
         }
     }