diff --git a/include/boost/fusion/functional/invocation/invoke.hpp b/include/boost/fusion/functional/invocation/invoke.hpp
index 2de4fced..c2e11408 100644
--- a/include/boost/fusion/functional/invocation/invoke.hpp
+++ b/include/boost/fusion/functional/invocation/invoke.hpp
@@ -41,6 +41,7 @@
 #include <boost/utility/result_of.hpp>
 
 #include <boost/fusion/support/category_of.hpp>
+#include <boost/fusion/support/detail/enabler.hpp>
 #include <boost/fusion/sequence/intrinsic/at.hpp>
 #include <boost/fusion/sequence/intrinsic/size.hpp>
 #include <boost/fusion/sequence/intrinsic/front.hpp>
@@ -52,29 +53,10 @@
 
 namespace boost { namespace fusion
 {
-    //~ namespace result_of
-    //~ {
-    //~     template <typename Function, class Sequence,
-    //~               class Enable = unspecified>
-    //~     struct invoke;
-    //~ }
-
-    //~ template <typename Function, class Sequence>
-    //~ inline typename result_of::invoke<Function, Sequence>::type
-    //~ invoke(Function, Sequence &);
-
-    //~ template <typename Function, class Sequence>
-    //~ inline typename result_of::invoke<Function, Sequence const>::type
-    //~ invoke(Function, Sequence const &);
-
-    //----- ---- --- -- - -  -   -
-
     namespace detail
     {
         namespace ft = function_types;
 
-        template <typename, typename T = void> struct always_void_ { typedef T type; };
-
         template<
             typename Function, class Sequence,
             int N = result_of::size<Sequence>::value,
@@ -161,14 +143,20 @@ namespace boost { namespace fusion
 
     namespace result_of
     {
-        template <typename Function, class Sequence,
-                  class Enable =
-                    typename detail::invoke_impl<
-                        typename boost::remove_reference<Function>::type, Sequence
-                      >::result_type>
-        struct invoke
+        template <typename Function, class Sequence, typename = void>
+        struct invoke;
+
+        template <typename Function, class Sequence>
+        struct invoke<Function, Sequence,
+                      typename detail::enabler<
+                          typename detail::invoke_impl<
+                              typename boost::remove_reference<Function>::type, Sequence
+                          >::result_type
+                      >::type>
         {
-            typedef Enable type;
+            typedef typename detail::invoke_impl<
+                typename boost::remove_reference<Function>::type, Sequence
+            >::result_type type;
         };
     }
 
@@ -207,7 +195,7 @@ namespace boost { namespace fusion
 
         template <typename Function, class Sequence>
         struct invoke_impl<Function,Sequence,N,false,true,
-            typename always_void_<
+            typename enabler<
                 typename boost::result_of<Function(BOOST_PP_ENUM(N,M,~)) >::type
               >::type>
         {
@@ -301,7 +289,7 @@ namespace boost { namespace fusion
 
         template <typename Function, class Sequence>
         struct invoke_impl<Function,Sequence,N,false,false,
-            typename always_void_<
+            typename enabler<
 #define L(z,j,data) typename invoke_param_types<Sequence,N>::BOOST_PP_CAT(T, j)
                 typename boost::result_of<Function(BOOST_PP_ENUM(N,L,~))>::type
               >::type>
diff --git a/include/boost/fusion/functional/invocation/invoke_function_object.hpp b/include/boost/fusion/functional/invocation/invoke_function_object.hpp
index a5c9510c..95e8cb92 100644
--- a/include/boost/fusion/functional/invocation/invoke_function_object.hpp
+++ b/include/boost/fusion/functional/invocation/invoke_function_object.hpp
@@ -25,6 +25,7 @@
 #include <boost/utility/result_of.hpp>
 
 #include <boost/fusion/support/category_of.hpp>
+#include <boost/fusion/support/detail/enabler.hpp>
 #include <boost/fusion/sequence/intrinsic/size.hpp>
 #include <boost/fusion/sequence/intrinsic/at.hpp>
 #include <boost/fusion/sequence/intrinsic/begin.hpp>
@@ -34,29 +35,13 @@
 
 namespace boost { namespace fusion
 {
-    namespace result_of
-    {
-        template <class Function, class Sequence> struct invoke_function_object;
-    }
-
-    template <class Function, class Sequence>
-    BOOST_FUSION_GPU_ENABLED
-    inline typename result_of::invoke_function_object<Function, Sequence>::type
-    invoke_function_object(Function, Sequence &);
-
-    template <class Function, class Sequence>
-    BOOST_FUSION_GPU_ENABLED
-    inline typename result_of::invoke_function_object<Function, Sequence const
-        >::type invoke_function_object(Function, Sequence const &);
-
-    //----- ---- --- -- - -  -   -
-
     namespace detail
     {
         template<
             class Function, class Sequence,
             int N = result_of::size<Sequence>::value,
-            bool RandomAccess = traits::is_random_access<Sequence>::value
+            bool RandomAccess = traits::is_random_access<Sequence>::value,
+            typename Enable = void
             >
         struct invoke_function_object_impl;
 
@@ -72,7 +57,16 @@ namespace boost { namespace fusion
 
     namespace result_of
     {
-        template <class Function, class Sequence> struct invoke_function_object
+        template <class Function, class Sequence, class Enable = void>
+        struct invoke_function_object;
+
+        template <class Function, class Sequence>
+        struct invoke_function_object<Function, Sequence,
+            typename detail::enabler<
+                typename detail::invoke_function_object_impl<
+                    typename boost::remove_reference<Function>::type, Sequence
+                >::result_type
+            >::type>
         {
             typedef typename detail::invoke_function_object_impl<
                 typename boost::remove_reference<Function>::type, Sequence
@@ -111,14 +105,18 @@ namespace boost { namespace fusion
 ///////////////////////////////////////////////////////////////////////////////
 #define N BOOST_PP_ITERATION()
 
+#define M(z,j,data)                                                             \
+        typename result_of::at_c<Sequence,j>::type
+
         template <class Function, class Sequence>
-        struct invoke_function_object_impl<Function,Sequence,N,true>
+        struct invoke_function_object_impl<Function,Sequence,N,true,
+            typename enabler<
+                typename boost::result_of<Function (BOOST_PP_ENUM(N,M,~)) >::type
+            >::type>
         {
         public:
 
             typedef typename boost::result_of<
-#define M(z,j,data)                                                             \
-        typename result_of::at_c<Sequence,j>::type
                 Function (BOOST_PP_ENUM(N,M,~)) >::type result_type;
 #undef M
 
@@ -148,8 +146,15 @@ namespace boost { namespace fusion
 
         };
 
+#define M(z,j,data)                                                             \
+            typename invoke_function_object_param_types<Sequence,N>::T ## j
+
         template <class Function, class Sequence>
-        struct invoke_function_object_impl<Function,Sequence,N,false>
+        struct invoke_function_object_impl<Function,Sequence,N,false,
+            typename enabler<
+                typename boost::result_of<Function (BOOST_PP_ENUM(N,M,~)) >::type
+            >::type>
+#undef M
         {
         private:
             typedef invoke_function_object_param_types<Sequence,N> seq;
diff --git a/include/boost/fusion/functional/invocation/invoke_procedure.hpp b/include/boost/fusion/functional/invocation/invoke_procedure.hpp
index bd3e49b9..ca5a9592 100644
--- a/include/boost/fusion/functional/invocation/invoke_procedure.hpp
+++ b/include/boost/fusion/functional/invocation/invoke_procedure.hpp
@@ -28,6 +28,7 @@
 #include <boost/function_types/parameter_types.hpp>
 
 #include <boost/fusion/support/category_of.hpp>
+#include <boost/fusion/support/detail/enabler.hpp>
 #include <boost/fusion/sequence/intrinsic/at.hpp>
 #include <boost/fusion/sequence/intrinsic/size.hpp>
 #include <boost/fusion/sequence/intrinsic/begin.hpp>
@@ -38,24 +39,6 @@
 
 namespace boost { namespace fusion
 {
-    namespace result_of
-    {
-        template <typename Function, class Sequence> struct invoke_procedure
-        {
-            typedef void type;
-        };
-    }
-
-    template <typename Function, class Sequence>
-    BOOST_FUSION_GPU_ENABLED
-    inline void invoke_procedure(Function, Sequence &);
-
-    template <typename Function, class Sequence>
-    BOOST_FUSION_GPU_ENABLED
-    inline void invoke_procedure(Function, Sequence const &);
-
-    //----- ---- --- -- - -  -   -
-
     namespace detail
     {
         namespace ft = function_types;
@@ -76,9 +59,27 @@ namespace boost { namespace fusion
 
     }
 
+    namespace result_of
+    {
+        template <typename Function, class Sequence, class Enable = void>
+        struct invoke_procedure;
+
+        template <typename Function, class Sequence>
+        struct invoke_procedure<Function, Sequence,
+            typename detail::enabler<
+                typename detail::invoke_procedure_impl<
+                    typename boost::remove_reference<Function>::type,Sequence
+                >::result_type
+            >::type>
+        {
+            typedef void type;
+        };
+    }
+
     template <typename Function, class Sequence>
     BOOST_FUSION_GPU_ENABLED
-    inline void invoke_procedure(Function f, Sequence & s)
+    inline typename result_of::invoke_procedure<Function, Sequence>::type
+    invoke_procedure(Function f, Sequence & s)
     {
         detail::invoke_procedure_impl<
                 typename boost::remove_reference<Function>::type,Sequence
@@ -87,7 +88,8 @@ namespace boost { namespace fusion
 
     template <typename Function, class Sequence>
     BOOST_FUSION_GPU_ENABLED
-    inline void invoke_procedure(Function f, Sequence const & s)
+    inline typename result_of::invoke_procedure<Function, Sequence const>::type
+    invoke_procedure(Function f, Sequence const & s)
     {
         detail::invoke_procedure_impl<
                 typename boost::remove_reference<Function>::type,Sequence const
@@ -110,6 +112,7 @@ namespace boost { namespace fusion
         template <typename Function, class Sequence>
         struct invoke_procedure_impl<Function,Sequence,N,false,true>
         {
+            typedef void result_type;
 
 #if N > 0
 
@@ -135,6 +138,8 @@ namespace boost { namespace fusion
         template <typename Function, class Sequence>
         struct invoke_procedure_impl<Function,Sequence,N,true,true>
         {
+            typedef void result_type;
+
             BOOST_FUSION_GPU_ENABLED
             static inline void call(Function & f, Sequence & s)
             {
@@ -155,6 +160,7 @@ namespace boost { namespace fusion
         template <typename Function, class Sequence>
         struct invoke_procedure_impl<Function,Sequence,N,false,false>
         {
+            typedef void result_type;
 
 #if N > 0
 
@@ -182,6 +188,8 @@ namespace boost { namespace fusion
         template <typename Function, class Sequence>
         struct invoke_procedure_impl<Function,Sequence,N,true,false>
         {
+            typedef void result_type;
+
             BOOST_FUSION_GPU_ENABLED
             static inline void call(Function & f, Sequence & s)
             {
diff --git a/include/boost/fusion/support/detail/enabler.hpp b/include/boost/fusion/support/detail/enabler.hpp
new file mode 100644
index 00000000..48b69f32
--- /dev/null
+++ b/include/boost/fusion/support/detail/enabler.hpp
@@ -0,0 +1,18 @@
+/*=============================================================================
+    Copyright (c) 2015 Kohei Takahashi
+
+    Use modification and distribution are subject to the Boost Software
+    License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
+    http://www.boost.org/LICENSE_1_0.txt).
+==============================================================================*/
+#ifndef FUSION_DETAIL_ENABLER_02082015_163810
+#define FUSION_DETAIL_ENABLER_02082015_163810
+
+namespace boost { namespace fusion { namespace detail
+{
+    template <typename, typename T = void>
+    struct enabler { typedef T type; };
+}}}
+
+#endif
+
diff --git a/test/compile_time/sfinae_friendly.hpp b/test/compile_time/sfinae_friendly.hpp
new file mode 100644
index 00000000..77b148b8
--- /dev/null
+++ b/test/compile_time/sfinae_friendly.hpp
@@ -0,0 +1,54 @@
+/*=============================================================================
+    Copyright (c) 2015 Kohei Takahashi
+
+    Use modification and distribution are subject to the Boost Software
+    License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
+    http://www.boost.org/LICENSE_1_0.txt).
+==============================================================================*/
+
+#ifndef FUSION_TEST_SFINAE_FRIENDLY_HPP
+#define FUSION_TEST_SFINAE_FRIENDLY_HPP
+
+#include <boost/config.hpp>
+#include <boost/mpl/bool.hpp>
+#include <boost/mpl/assert.hpp>
+#include <boost/fusion/support/detail/result_of.hpp>
+
+#if !defined(BOOST_NO_SFINAE) && !defined(BOOST_FUSION_NO_DECLTYPE_BASED_RESULT_OF)
+
+#include <boost/fusion/container/vector.hpp>
+
+namespace sfinae_friendly
+{
+    template <typename, typename T = void> struct void_ { typedef T type; };
+
+    template <typename> struct arg_;
+    template <typename R, typename T> struct arg_<R(T)> { typedef T type; };
+
+    template <typename Traits, typename = void>
+    struct check
+        : boost::mpl::true_ { };
+
+    template <typename Traits>
+    struct check<Traits, typename void_<typename Traits::type>::type>
+        : boost::mpl::false_ { };
+
+    struct unspecified {};
+    typedef boost::fusion::vector<> v0;
+    typedef boost::fusion::vector<unspecified> v1;
+    typedef boost::fusion::vector<unspecified, unspecified> v2;
+    typedef boost::fusion::vector<unspecified, unspecified, unspecified> v3;
+}
+
+#define SFINAE_FRIENDLY_ASSERT(Traits) \
+    BOOST_MPL_ASSERT((::sfinae_friendly::check<typename ::sfinae_friendly::arg_<void Traits>::type>))
+
+#else
+
+#define SFINAE_FRIENDLY_ASSERT(Traits) \
+    BOOST_MPL_ASSERT((boost::mpl::true_))
+
+#endif
+
+#endif // FUSION_TEST_SFINAE_FRIENDLY_HPP
+
diff --git a/test/functional/invoke.cpp b/test/functional/invoke.cpp
index 5975e79b..2a94539f 100644
--- a/test/functional/invoke.cpp
+++ b/test/functional/invoke.cpp
@@ -82,11 +82,10 @@ struct fobj
     int operator()(int i, object const &, object_nc &);
     int operator()(int i, object const &, object_nc &) const;
 };
-// FIXME:
-//SFINAE_FRIENDLY_ASSERT((fusion::result_of::invoke<fobj, sfinae_friendly::v0>));
-//SFINAE_FRIENDLY_ASSERT((fusion::result_of::invoke<fobj, sfinae_friendly::v1>));
-//SFINAE_FRIENDLY_ASSERT((fusion::result_of::invoke<fobj, sfinae_friendly::v2>));
-//SFINAE_FRIENDLY_ASSERT((fusion::result_of::invoke<fobj, sfinae_friendly::v3>));
+SFINAE_FRIENDLY_ASSERT((fusion::result_of::invoke<fobj, sfinae_friendly::v0>));
+SFINAE_FRIENDLY_ASSERT((fusion::result_of::invoke<fobj, sfinae_friendly::v1>));
+SFINAE_FRIENDLY_ASSERT((fusion::result_of::invoke<fobj, sfinae_friendly::v2>));
+SFINAE_FRIENDLY_ASSERT((fusion::result_of::invoke<fobj, sfinae_friendly::v3>));
 
 
 struct nullary_fobj
@@ -96,10 +95,9 @@ struct nullary_fobj
     int operator()()       { return 0; }
     int operator()() const { return 1; }
 };
-// FIXME:
-//SFINAE_FRIENDLY_ASSERT((fusion::result_of::invoke<nullary_fobj, sfinae_friendly::v1>));
-//SFINAE_FRIENDLY_ASSERT((fusion::result_of::invoke<nullary_fobj, sfinae_friendly::v2>));
-//SFINAE_FRIENDLY_ASSERT((fusion::result_of::invoke<nullary_fobj, sfinae_friendly::v3>));
+SFINAE_FRIENDLY_ASSERT((fusion::result_of::invoke<nullary_fobj, sfinae_friendly::v1>));
+SFINAE_FRIENDLY_ASSERT((fusion::result_of::invoke<nullary_fobj, sfinae_friendly::v2>));
+SFINAE_FRIENDLY_ASSERT((fusion::result_of::invoke<nullary_fobj, sfinae_friendly::v3>));
 
 
 struct fobj_nc
@@ -118,11 +116,10 @@ struct fobj_nc
     int operator()(int i)       { return 14 + i; }
     int operator()(int i) const { return 15 + i; }
 };
-// FIXME:
-//SFINAE_FRIENDLY_ASSERT((fusion::result_of::invoke<fobj_nc, sfinae_friendly::v0>));
-//SFINAE_FRIENDLY_ASSERT((fusion::result_of::invoke<fobj_nc, sfinae_friendly::v1>));
-//SFINAE_FRIENDLY_ASSERT((fusion::result_of::invoke<fobj_nc, sfinae_friendly::v2>));
-//SFINAE_FRIENDLY_ASSERT((fusion::result_of::invoke<fobj_nc, sfinae_friendly::v3>));
+SFINAE_FRIENDLY_ASSERT((fusion::result_of::invoke<fobj_nc, sfinae_friendly::v0>));
+SFINAE_FRIENDLY_ASSERT((fusion::result_of::invoke<fobj_nc, sfinae_friendly::v1>));
+SFINAE_FRIENDLY_ASSERT((fusion::result_of::invoke<fobj_nc, sfinae_friendly::v2>));
+SFINAE_FRIENDLY_ASSERT((fusion::result_of::invoke<fobj_nc, sfinae_friendly::v3>));
 
 
 struct nullary_fobj_nc
@@ -133,10 +130,9 @@ struct nullary_fobj_nc
     int operator()()       { return 12; }
     int operator()() const { return 13; }
 };
-// FIXME:
-//SFINAE_FRIENDLY_ASSERT((fusion::result_of::invoke<nullary_fobj_nc, sfinae_friendly::v1>));
-//SFINAE_FRIENDLY_ASSERT((fusion::result_of::invoke<nullary_fobj_nc, sfinae_friendly::v2>));
-//SFINAE_FRIENDLY_ASSERT((fusion::result_of::invoke<nullary_fobj_nc, sfinae_friendly::v3>));
+SFINAE_FRIENDLY_ASSERT((fusion::result_of::invoke<nullary_fobj_nc, sfinae_friendly::v1>));
+SFINAE_FRIENDLY_ASSERT((fusion::result_of::invoke<nullary_fobj_nc, sfinae_friendly::v2>));
+SFINAE_FRIENDLY_ASSERT((fusion::result_of::invoke<nullary_fobj_nc, sfinae_friendly::v3>));
 
 
 int nullary() { return 16; }
diff --git a/test/functional/invoke_function_object.cpp b/test/functional/invoke_function_object.cpp
index 176be186..7c75f06d 100644
--- a/test/functional/invoke_function_object.cpp
+++ b/test/functional/invoke_function_object.cpp
@@ -84,11 +84,9 @@ struct fobj
     int operator()(int i, object const &, object_nc &);
     int operator()(int i, object const &, object_nc &) const;
 };
-// FIXME:
-//SFINAE_FRIENDLY_ASSERT((fusion::result_of::invoke_function_object<fobj, sfinae_friendly::v0>));
-//SFINAE_FRIENDLY_ASSERT((fusion::result_of::invoke_function_object<fobj, sfinae_friendly::v1>));
-//SFINAE_FRIENDLY_ASSERT((fusion::result_of::invoke_function_object<fobj, sfinae_friendly::v2>));
-//SFINAE_FRIENDLY_ASSERT((fusion::result_of::invoke_function_object<fobj, sfinae_friendly::v3>));
+SFINAE_FRIENDLY_ASSERT((fusion::result_of::invoke_function_object<fobj, sfinae_friendly::v1>));
+SFINAE_FRIENDLY_ASSERT((fusion::result_of::invoke_function_object<fobj, sfinae_friendly::v2>));
+SFINAE_FRIENDLY_ASSERT((fusion::result_of::invoke_function_object<fobj, sfinae_friendly::v3>));
 
 struct nullary_fobj
 {
@@ -97,10 +95,9 @@ struct nullary_fobj
     int operator()()       { return 0; }
     int operator()() const { return 1; }
 };
-// FIXME:
-//SFINAE_FRIENDLY_ASSERT((fusion::result_of::invoke_function_object<nullary_fobj, sfinae_friendly::v1>));
-//SFINAE_FRIENDLY_ASSERT((fusion::result_of::invoke_function_object<nullary_fobj, sfinae_friendly::v2>));
-//SFINAE_FRIENDLY_ASSERT((fusion::result_of::invoke_function_object<nullary_fobj, sfinae_friendly::v3>));
+SFINAE_FRIENDLY_ASSERT((fusion::result_of::invoke_function_object<nullary_fobj, sfinae_friendly::v1>));
+SFINAE_FRIENDLY_ASSERT((fusion::result_of::invoke_function_object<nullary_fobj, sfinae_friendly::v2>));
+SFINAE_FRIENDLY_ASSERT((fusion::result_of::invoke_function_object<nullary_fobj, sfinae_friendly::v3>));
 
 struct fobj_nc
       : boost::noncopyable
@@ -118,11 +115,10 @@ struct fobj_nc
     int operator()(int i)       { return 14 + i; }
     int operator()(int i) const { return 15 + i; }
 };
-// FIXME:
-//SFINAE_FRIENDLY_ASSERT((fusion::result_of::invoke_function_object<fobj_nc, sfinae_friendly::v0>));
-//SFINAE_FRIENDLY_ASSERT((fusion::result_of::invoke_function_object<fobj_nc, sfinae_friendly::v1>));
-//SFINAE_FRIENDLY_ASSERT((fusion::result_of::invoke_function_object<fobj_nc, sfinae_friendly::v2>));
-//SFINAE_FRIENDLY_ASSERT((fusion::result_of::invoke_function_object<fobj_nc, sfinae_friendly::v3>));
+SFINAE_FRIENDLY_ASSERT((fusion::result_of::invoke_function_object<fobj_nc, sfinae_friendly::v0>));
+SFINAE_FRIENDLY_ASSERT((fusion::result_of::invoke_function_object<fobj_nc, sfinae_friendly::v1>));
+SFINAE_FRIENDLY_ASSERT((fusion::result_of::invoke_function_object<fobj_nc, sfinae_friendly::v2>));
+SFINAE_FRIENDLY_ASSERT((fusion::result_of::invoke_function_object<fobj_nc, sfinae_friendly::v3>));
 
 struct nullary_fobj_nc
       : boost::noncopyable
@@ -132,10 +128,9 @@ struct nullary_fobj_nc
     int operator()()       { return 12; }
     int operator()() const { return 13; }
 };
-// FIXME:
-//SFINAE_FRIENDLY_ASSERT((fusion::result_of::invoke_function_object<nullary_fobj_nc, sfinae_friendly::v1>));
-//SFINAE_FRIENDLY_ASSERT((fusion::result_of::invoke_function_object<nullary_fobj_nc, sfinae_friendly::v2>));
-//SFINAE_FRIENDLY_ASSERT((fusion::result_of::invoke_function_object<nullary_fobj_nc, sfinae_friendly::v3>));
+SFINAE_FRIENDLY_ASSERT((fusion::result_of::invoke_function_object<nullary_fobj_nc, sfinae_friendly::v1>));
+SFINAE_FRIENDLY_ASSERT((fusion::result_of::invoke_function_object<nullary_fobj_nc, sfinae_friendly::v2>));
+SFINAE_FRIENDLY_ASSERT((fusion::result_of::invoke_function_object<nullary_fobj_nc, sfinae_friendly::v3>));
 
 
 typedef int         element1_type;