diff --git a/build/vc100/turtle.vcxproj b/build/vc100/turtle.vcxproj
index a9906d5..c453ca7 100644
--- a/build/vc100/turtle.vcxproj
+++ b/build/vc100/turtle.vcxproj
@@ -46,6 +46,7 @@
     <ClInclude Include="..\..\turtle\detail\parameters.hpp" />
     <ClInclude Include="..\..\turtle\detail\parent.hpp" />
     <ClInclude Include="..\..\turtle\detail\root.hpp" />
+    <ClInclude Include="..\..\turtle\detail\sequence_impl.hpp" />
     <ClInclude Include="..\..\turtle\detail\signature.hpp" />
     <ClInclude Include="..\..\turtle\detail\type_name.hpp" />
     <ClInclude Include="..\..\turtle\detail\verifiable.hpp" />
diff --git a/build/vc100/turtle.vcxproj.filters b/build/vc100/turtle.vcxproj.filters
index f0de3b3..ac96323 100644
--- a/build/vc100/turtle.vcxproj.filters
+++ b/build/vc100/turtle.vcxproj.filters
@@ -130,5 +130,8 @@
     <ClInclude Include="..\..\turtle\detail\parameter.hpp">
       <Filter>Source Files\detail</Filter>
     </ClInclude>
+    <ClInclude Include="..\..\turtle\detail\sequence_impl.hpp">
+      <Filter>Source Files\detail</Filter>
+    </ClInclude>
   </ItemGroup>
 </Project>
\ No newline at end of file
diff --git a/turtle/detail/sequence_impl.hpp b/turtle/detail/sequence_impl.hpp
new file mode 100644
index 0000000..e7048a8
--- /dev/null
+++ b/turtle/detail/sequence_impl.hpp
@@ -0,0 +1,56 @@
+// http://turtle.sourceforge.net
+//
+// Copyright Mathieu Champlon 2012
+//
+// 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_SEQUENCE_IMPL_HPP_INCLUDED
+#define MOCK_SEQUENCE_IMPL_HPP_INCLUDED
+
+#include <boost/noncopyable.hpp>
+#include <boost/shared_ptr.hpp>
+#include <algorithm>
+#include <vector>
+
+namespace mock
+{
+namespace detail
+{
+    class sequence_impl : private boost::noncopyable
+    {
+    public:
+        void add( void* e )
+        {
+            elements_.push_back( e );
+        }
+        void remove( void* e )
+        {
+            elements_.erase( std::remove( elements_.begin(),
+                elements_.end(), e ), elements_.end() );
+        }
+
+        bool is_valid( const void* e ) const
+        {
+            return std::find( elements_.begin(), elements_.end(), e )
+                != elements_.end();
+        }
+
+        void invalidate( const void* e )
+        {
+            elements_type::iterator it =
+                std::find( elements_.begin(), elements_.end(), e );
+            if( it != elements_.end() )
+                elements_.erase( elements_.begin(), it );
+        }
+
+    private:
+        typedef std::vector< void* > elements_type;
+
+        elements_type elements_;
+    };
+}
+} // mock
+
+#endif // MOCK_SEQUENCE_IMPL_HPP_INCLUDED
diff --git a/turtle/sequence.hpp b/turtle/sequence.hpp
index 4d4e86d..b5e5408 100644
--- a/turtle/sequence.hpp
+++ b/turtle/sequence.hpp
@@ -9,49 +9,11 @@
 #ifndef MOCK_SEQUENCE_HPP_INCLUDED
 #define MOCK_SEQUENCE_HPP_INCLUDED
 
-#include <boost/noncopyable.hpp>
+#include "detail/sequence_impl.hpp"
 #include <boost/shared_ptr.hpp>
-#include <algorithm>
-#include <vector>
 
 namespace mock
 {
-namespace detail
-{
-    class sequence_impl : private boost::noncopyable
-    {
-    public:
-        void add( void* e )
-        {
-            elements_.push_back( e );
-        }
-        void remove( void* e )
-        {
-            elements_.erase( std::remove( elements_.begin(),
-                elements_.end(), e ), elements_.end() );
-        }
-
-        bool is_valid( const void* e ) const
-        {
-            return std::find( elements_.begin(), elements_.end(), e )
-                != elements_.end();
-        }
-
-        void invalidate( const void* e )
-        {
-            elements_type::iterator it =
-                std::find( elements_.begin(), elements_.end(), e );
-            if( it != elements_.end() )
-                elements_.erase( elements_.begin(), it );
-        }
-
-    private:
-        typedef std::vector< void* > elements_type;
-
-        elements_type elements_;
-    };
-}
-
     class sequence
     {
     public: