diff --git a/src/lib/meta/function-erasure.hpp b/src/lib/meta/function-erasure.hpp
index f86de74b9..6d3729160 100644
--- a/src/lib/meta/function-erasure.hpp
+++ b/src/lib/meta/function-erasure.hpp
@@ -64,6 +64,7 @@ namespace lumiera {
 namespace typelist{
   
   using std::tr1::function;
+  using util::unConst;
   
   
   
@@ -100,8 +101,6 @@ namespace typelist{
    * Using this policy allows to store arbitrary complex functor objects
    * embedded within a neutral container and retrieving them later type-safe.
    * The price to pay is vtable access and heap storage of function arguments.
-   * 
-   * @note the bool conversion and #isValid are highly implementation dependent
    */
   class StoreFunction
     : public lib::BoolCheckable<StoreFunction>
@@ -112,6 +111,7 @@ namespace typelist{
           enum { SIZE = sizeof(function<void(void)>) };
           char storage_[SIZE];
           virtual ~Holder() {}
+          virtual bool isValid()  const { return false; }
         };
       
       /** embedding the concrete functor object */
@@ -129,6 +129,12 @@ namespace typelist{
             {
               get().~Functor();
             }
+          bool
+          isValid()  const
+            {
+              const Functor& func (unConst(this)->get());
+              return bool(func);
+            }
           Functor&
           get()
             {
@@ -161,9 +167,9 @@ namespace typelist{
         }
       
       bool
-      isValid()  const   ///< @note implementation dependent!!
+      isValid()  const
         {
-          return reinterpret_cast<void*> (holder_.storage_[0]);
+          return holder_.isValid();
         }
     };
   
diff --git a/tests/lib/meta/function-erasure-test.cpp b/tests/lib/meta/function-erasure-test.cpp
index 43320c453..aadd03e14 100644
--- a/tests/lib/meta/function-erasure-test.cpp
+++ b/tests/lib/meta/function-erasure-test.cpp
@@ -47,9 +47,9 @@ namespace test {
   typedef FunErasure<StoreUncheckedFunPtr> Evoid;
   
   template<class HOL>
-  struct BuildEmptyHolder       { typedef long (*Type)(int,char); };
+  struct BuildEmptyFunctor       { typedef long (*Type)(int,char); };
   template<>
-  struct BuildEmptyHolder<Efun> { typedef function<long(int,char)> Type; };
+  struct BuildEmptyFunctor<Efun> { typedef function<long(int,char)> Type; };
   
   
   /***********************************************************************
@@ -210,8 +210,9 @@ namespace test {
         {
           // fabricate an unbound functor...
           
-          typedef typename BuildEmptyHolder<HOL>::Type EmptyHolder;
-          EmptyHolder emptyHolder;
+          typedef typename BuildEmptyFunctor<HOL>::Type NoFunc;
+          NoFunc noFunction;
+          HOL emptyHolder (noFunction);
           ASSERT (!emptyHolder);
           ASSERT ( h1 );
           ASSERT ( h2 );