diff --git a/src/core/callback.h b/src/core/callback.h
index 526c022a3..64e92ccd8 100644
--- a/src/core/callback.h
+++ b/src/core/callback.h
@@ -226,6 +226,7 @@ class CallbackBase {
 public:
   virtual ~CallbackBase () {}
   virtual CallbackImplBase *PeekImpl (void) const = 0;
+  virtual Ptr<CallbackImplBase> GetImpl (void) const = 0;
 };
 
 /**
@@ -341,6 +342,9 @@ public:
       }
     *this = Callback<R,T1,T2,T3,T4,T5> (impl);
   }
+  virtual Ptr<CallbackImplBase>GetImpl (void) const {
+    return m_impl;
+  }
 private:
   virtual CallbackImpl<R,T1,T2,T3,T4,T5> *PeekImpl (void) const {
     return PeekPointer (m_impl);