diff --git a/build/vc100/turtle.vcxproj b/build/vc100/turtle.vcxproj
index adfe01d..c714e46 100644
--- a/build/vc100/turtle.vcxproj
+++ b/build/vc100/turtle.vcxproj
@@ -27,11 +27,11 @@
     <ClInclude Include="..\..\turtle\constraint.hpp" />
     <ClInclude Include="..\..\turtle\constraints.hpp" />
     <ClInclude Include="..\..\turtle\default_error.hpp" />
-    <ClInclude Include="..\..\turtle\detail\args.hpp" />
     <ClInclude Include="..\..\turtle\detail\child.hpp" />
     <ClInclude Include="..\..\turtle\detail\context.hpp" />
     <ClInclude Include="..\..\turtle\detail\group.hpp" />
     <ClInclude Include="..\..\turtle\detail\lambda.hpp" />
+    <ClInclude Include="..\..\turtle\detail\parameters.hpp" />
     <ClInclude Include="..\..\turtle\detail\parent.hpp" />
     <ClInclude Include="..\..\turtle\detail\root.hpp" />
     <ClInclude Include="..\..\turtle\detail\signature.hpp" />
diff --git a/build/vc100/turtle.vcxproj.filters b/build/vc100/turtle.vcxproj.filters
index 4bc1207..77db42a 100644
--- a/build/vc100/turtle.vcxproj.filters
+++ b/build/vc100/turtle.vcxproj.filters
@@ -70,9 +70,6 @@
     <ClInclude Include="..\..\turtle\detail\lambda.hpp">
       <Filter>Source Files\detail</Filter>
     </ClInclude>
-    <ClInclude Include="..\..\turtle\detail\args.hpp">
-      <Filter>Source Files\detail</Filter>
-    </ClInclude>
     <ClInclude Include="..\..\turtle\detail\child.hpp">
       <Filter>Source Files\detail</Filter>
     </ClInclude>
@@ -97,5 +94,8 @@
     <ClInclude Include="..\..\turtle\detail\yes_no_type.hpp">
       <Filter>Source Files\detail</Filter>
     </ClInclude>
+    <ClInclude Include="..\..\turtle\detail\parameters.hpp">
+      <Filter>Source Files\detail</Filter>
+    </ClInclude>
   </ItemGroup>
 </Project>
\ No newline at end of file
diff --git a/build/vc100/turtle_test.vcxproj b/build/vc100/turtle_test.vcxproj
index 943af8b..7963ae4 100644
--- a/build/vc100/turtle_test.vcxproj
+++ b/build/vc100/turtle_test.vcxproj
@@ -22,7 +22,7 @@
     <ClInclude Include="..\..\test\mock_error.hpp" />
   </ItemGroup>
   <ItemGroup>
-    <ClCompile Include="..\..\test\detail\test_args.cpp" />
+    <ClCompile Include="..\..\test\detail\test_parameters.cpp" />
     <ClCompile Include="..\..\test\detail\test_signature.cpp" />
     <ClCompile Include="..\..\test\detail\test_type_name.cpp" />
     <ClCompile Include="..\..\test\test_constraints.cpp" />
diff --git a/build/vc100/turtle_test.vcxproj.filters b/build/vc100/turtle_test.vcxproj.filters
index 04dbbf0..c547135 100644
--- a/build/vc100/turtle_test.vcxproj.filters
+++ b/build/vc100/turtle_test.vcxproj.filters
@@ -51,10 +51,10 @@
     <ClCompile Include="..\..\test\detail\test_signature.cpp">
       <Filter>Source Files\detail</Filter>
     </ClCompile>
-    <ClCompile Include="..\..\test\detail\test_args.cpp">
+    <ClCompile Include="..\..\test\detail\test_type_name.cpp">
       <Filter>Source Files\detail</Filter>
     </ClCompile>
-    <ClCompile Include="..\..\test\detail\test_type_name.cpp">
+    <ClCompile Include="..\..\test\detail\test_parameters.cpp">
       <Filter>Source Files\detail</Filter>
     </ClCompile>
   </ItemGroup>
diff --git a/test/detail/test_args.cpp b/test/detail/test_args.cpp
deleted file mode 100644
index e19232b..0000000
--- a/test/detail/test_args.cpp
+++ /dev/null
@@ -1,20 +0,0 @@
-// http://turtle.sourceforge.net
-//
-// Copyright Mathieu Champlon 2009
-//
-// Distributed under 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)
-
-#include <turtle/detail/args.hpp>
-#include <boost/test/auto_unit_test.hpp>
-#include <boost/mpl/assert.hpp>
-
-BOOST_MPL_ASSERT(( boost::is_same< float, mock::detail::arg< void( float ), 1, 1 >::type > ));
-BOOST_MPL_ASSERT(( boost::is_same< float, mock::detail::arg< void( float, int ), 1, 2 >::type > ));
-BOOST_MPL_ASSERT(( boost::is_same< int, mock::detail::arg< void( float, int ), 2, 2 >::type > ));
-BOOST_MPL_ASSERT(( boost::is_same< mock::detail::invalid_type, mock::detail::arg< void( float ), 1, 2 >::type > ));
-BOOST_MPL_ASSERT(( boost::is_same< mock::detail::invalid_type, mock::detail::arg< void( float ), 2, 2 >::type > ));
-BOOST_MPL_ASSERT(( boost::is_same< mock::detail::invalid_type, mock::detail::arg< void( float, int ), 1, 1 >::type > ));
-BOOST_MPL_ASSERT(( boost::is_same< mock::detail::invalid_type, mock::detail::arg< void( float, int ), 1, 3 >::type > ));
-BOOST_MPL_ASSERT(( boost::is_same< mock::detail::invalid_type, mock::detail::arg< void( float, int ), 2, 3 >::type > ));
diff --git a/test/detail/test_parameters.cpp b/test/detail/test_parameters.cpp
new file mode 100644
index 0000000..005a9a0
--- /dev/null
+++ b/test/detail/test_parameters.cpp
@@ -0,0 +1,15 @@
+// http://turtle.sourceforge.net
+//
+// Copyright Mathieu Champlon 2009
+//
+// Distributed under 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)
+
+#include <turtle/detail/parameters.hpp>
+#include <boost/test/auto_unit_test.hpp>
+#include <boost/mpl/assert.hpp>
+
+BOOST_MPL_ASSERT(( boost::is_same< float, mock::detail::parameters< void( float ), 1 >::at< 0 >::type > ));
+BOOST_MPL_ASSERT(( boost::is_same< float, mock::detail::parameters< void( float, int ), 2 >::at< 0 >::type > ));
+BOOST_MPL_ASSERT(( boost::is_same< int, mock::detail::parameters< void( float, int ), 2 >::at< 1 >::type > ));
diff --git a/turtle/detail/args.hpp b/turtle/detail/args.hpp
deleted file mode 100644
index 82e788c..0000000
--- a/turtle/detail/args.hpp
+++ /dev/null
@@ -1,69 +0,0 @@
-// http://turtle.sourceforge.net
-//
-// Copyright Mathieu Champlon 2010
-//
-// Distributed under 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 MOCK_ARGS_HPP_INCLUDED
-#define MOCK_ARGS_HPP_INCLUDED
-
-#include <boost/function_types/parameter_types.hpp>
-#include <boost/function_types/function_arity.hpp>
-#include <boost/preprocessor/arithmetic/inc.hpp>
-#include <boost/mpl/at.hpp>
-
-namespace mock
-{
-namespace detail
-{
-    struct invalid_type
-    {
-    private:
-        invalid_type();
-    };
-
-    template< typename S, int n, bool B >
-    struct arg_imp
-    {
-        typedef invalid_type type;
-    };
-    template< typename S, int n >
-    struct arg_imp< S, n, true >
-    {
-        typedef BOOST_DEDUCED_TYPENAME
-            boost::mpl::at_c<
-                BOOST_DEDUCED_TYPENAME
-                    boost::function_types::parameter_types< S >,
-                n - 1
-            >::type type;
-    };
-    template< typename S, int n, int N >
-    struct arg :
-        arg_imp< S, n, boost::function_types::function_arity< S >::value == N >
-    {
-        BOOST_MPL_ASSERT_RELATION( n, >, 0 );
-        BOOST_MPL_ASSERT_RELATION( n, <=, N );
-    };
-}
-} // mock
-
-#define MOCK_ARG(N, n, S, tpn) \
-    BOOST_PP_COMMA_IF(n) tpn \
-        mock::detail::arg< S, BOOST_PP_INC(n), N >::type p##n
-#define MOCK_ARG_PROXY(z, n, d) \
-    MOCK_ARG( \
-        BOOST_PP_ARRAY_ELEM(0, d), \
-        n, \
-        BOOST_PP_ARRAY_ELEM(1, d), \
-        BOOST_PP_ARRAY_ELEM(2, d) )
-
-#define MOCK_ARGS(n, S, tpn) \
-    BOOST_PP_REPEAT(n, MOCK_ARG_PROXY, (3, (n, S, tpn)))
-
-#define MOCK_DECL(M, n, S, c, tpn) \
-    tpn boost::function_types::result_type< S >::type M( \
-        MOCK_ARGS(n, S, tpn) ) c
-
-#endif // MOCK_ARGS_HPP_INCLUDED
diff --git a/turtle/detail/parameters.hpp b/turtle/detail/parameters.hpp
new file mode 100644
index 0000000..f43d0a6
--- /dev/null
+++ b/turtle/detail/parameters.hpp
@@ -0,0 +1,40 @@
+// http://turtle.sourceforge.net
+//
+// Copyright Mathieu Champlon 2010
+//
+// Distributed under 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 MOCK_PARAMETERS_HPP_INCLUDED
+#define MOCK_PARAMETERS_HPP_INCLUDED
+
+#include <boost/function_types/parameter_types.hpp>
+#include <boost/function_types/function_arity.hpp>
+#include <boost/mpl/at.hpp>
+
+namespace mock
+{
+namespace detail
+{
+    template< typename Signature, int Arity >
+    struct parameters
+    {
+        BOOST_MPL_ASSERT_RELATION( Arity, ==,
+            boost::function_types::function_arity< Signature >::value );
+
+        template< int n >
+        struct at
+        {
+            typedef BOOST_DEDUCED_TYPENAME
+                boost::mpl::at_c<
+                    BOOST_DEDUCED_TYPENAME
+                        boost::function_types::parameter_types< Signature >,
+                    n
+                >::type type;
+        };
+    };
+}
+} // mock
+
+#endif // MOCK_PARAMETERS_HPP_INCLUDED
diff --git a/turtle/mock.hpp b/turtle/mock.hpp
index 1a51167..3d7f7e7 100644
--- a/turtle/mock.hpp
+++ b/turtle/mock.hpp
@@ -14,7 +14,7 @@
 #include "object.hpp"
 #include "function.hpp"
 #include "detail/type_name.hpp"
-#include "detail/args.hpp"
+#include "detail/parameters.hpp"
 #include "detail/signature.hpp"
 #include <boost/preprocessor/repetition/repeat.hpp>
 #include <boost/preprocessor/stringize.hpp>
@@ -66,6 +66,17 @@ namespace detail
         return t##_mock_; \
     }
 
+#define MOCK_PARAM(z, n, d) \
+    BOOST_PP_COMMA_IF(n) d::at< n >::type p##n
+
+#define MOCK_PARAMS(n, S, tpn) \
+    BOOST_PP_REPEAT(n, MOCK_PARAM, \
+        tpn mock::detail::parameters< S BOOST_PP_COMMA() n >)
+
+#define MOCK_DECL(M, n, S, c, tpn) \
+    tpn boost::function_types::result_type< S >::type M( \
+        MOCK_PARAMS(n, S, tpn) ) c
+
 #define MOCK_METHOD_AUX(M, n, S, t, c, tpn) \
     MOCK_DECL(M, n, S, c, tpn) \
     { \
@@ -119,7 +130,7 @@ namespace detail
 
 #define MOCK_CONSTRUCTOR_AUX(T, n, A, t, tpn) \
     MOCK_FUNCTION_HELPER(void A, t, static) \
-    T( MOCK_ARGS(n, void A, tpn) ) \
+    T( MOCK_PARAMS(n, void A, tpn) ) \
     { \
         MOCK_HELPER(t)( BOOST_PP_ENUM_PARAMS(n, p) ); \
     }