diff --git a/src/injectpp/config.hpp b/src/injectpp/config.hpp
index 68b5da5..a2ca5cc 100644
--- a/src/injectpp/config.hpp
+++ b/src/injectpp/config.hpp
@@ -7,8 +7,8 @@
 
 namespace nt { namespace ioc {
 
-template<class T, class ...Deps>
-std::unique_ptr<T>
+template<class U, class T, class ...Deps>
+std::unique_ptr<U>
 default_factory(Deps*... deps)
 {
     return std::make_unique<T>(deps...);
@@ -17,10 +17,16 @@ default_factory(Deps*... deps)
 class Config
 {
 public:
+    template<class Base, class InstanceType, class ...Deps>
+    void add_as()
+    {
+        add(default_factory<Base, InstanceType, Deps...>);
+    }
+
     template<class InstanceType, class ...Deps>
     void add()
     {
-        add(default_factory<InstanceType, Deps...>);
+        add(default_factory<InstanceType, InstanceType, Deps...>);
     }
 
     template<class InstanceType, class Deleter, class ...Deps>