diff --git a/build/vc80/turtle.vcproj b/build/vc80/turtle.vcproj
index 8d5bf6c..b44e6e4 100644
--- a/build/vc80/turtle.vcproj
+++ b/build/vc80/turtle.vcproj
@@ -212,10 +212,6 @@
 				RelativePath="..\..\src\libraries\turtle\object.hpp"
 				>
 			</File>
-			<File
-				RelativePath="..\..\src\libraries\turtle\orderable.hpp"
-				>
-			</File>
 			<File
 				RelativePath="..\..\src\libraries\turtle\placeholder.hpp"
 				>
@@ -228,6 +224,10 @@
 				RelativePath="..\..\src\libraries\turtle\sequence.hpp"
 				>
 			</File>
+			<File
+				RelativePath="..\..\src\libraries\turtle\sequenceable.hpp"
+				>
+			</File>
 			<File
 				RelativePath="..\..\src\libraries\turtle\type_name.hpp"
 				>
diff --git a/build/vc80/turtle_test.vcproj b/build/vc80/turtle_test.vcproj
index 706efb0..27fe1ff 100644
--- a/build/vc80/turtle_test.vcproj
+++ b/build/vc80/turtle_test.vcproj
@@ -52,6 +52,7 @@
 				ProgramDataBaseFileName="$(IntDir)/$(ProjectName).pdb"
 				WarningLevel="4"
 				SuppressStartupBanner="true"
+				Detect64BitPortabilityProblems="true"
 				DebugInformationFormat="3"
 			/>
 			<Tool
@@ -135,6 +136,7 @@
 				ProgramDataBaseFileName="$(IntDir)/$(ProjectName).pdb"
 				WarningLevel="4"
 				SuppressStartupBanner="true"
+				Detect64BitPortabilityProblems="true"
 				DebugInformationFormat="3"
 			/>
 			<Tool
diff --git a/src/libraries/turtle/expectation.hpp b/src/libraries/turtle/expectation.hpp
index 90f893f..df2d24b 100644
--- a/src/libraries/turtle/expectation.hpp
+++ b/src/libraries/turtle/expectation.hpp
@@ -28,7 +28,7 @@ namespace mock
 {
 namespace detail
 {
-    class expectation_base : private orderable
+    class expectation_base : private sequenceable
     {
     public:
         expectation_base()
diff --git a/src/libraries/turtle/invocation.hpp b/src/libraries/turtle/invocation.hpp
index d833923..2947413 100644
--- a/src/libraries/turtle/invocation.hpp
+++ b/src/libraries/turtle/invocation.hpp
@@ -35,6 +35,7 @@ namespace detail
         virtual bool is_valid() const = 0;
 
         // Verify invocation
+        // returns false if the verification fails
         virtual bool verify() const = 0;
 
         friend inline std::ostream& operator<<( std::ostream& s, const invocation& i )
diff --git a/src/libraries/turtle/sequence.hpp b/src/libraries/turtle/sequence.hpp
index 59066a8..6ab526e 100644
--- a/src/libraries/turtle/sequence.hpp
+++ b/src/libraries/turtle/sequence.hpp
@@ -9,7 +9,7 @@
 #ifndef MOCK_SEQUENCE_HPP_INCLUDED
 #define MOCK_SEQUENCE_HPP_INCLUDED
 
-#include "orderable.hpp"
+#include "sequenceable.hpp"
 #include <vector>
 #include <algorithm>
 
@@ -20,50 +20,49 @@ namespace mock
     public:
         ~sequence()
         {
-            for( elements_it it = elements_.begin();
-                it != elements_.end(); ++it )
+            for( orderables_it it = orderables_.begin();
+                it != orderables_.end(); ++it )
                 (*it)->remove( *this );
-            for( elements_it it = called_.begin();
+            for( orderables_it it = called_.begin();
                 it != called_.end(); ++it )
                 (*it)->remove( *this );
         }
 
-        void add( detail::orderable& e )
+        void add( detail::sequenceable& o )
         {
-            elements_.push_back( &e );
+            orderables_.push_back( &o );
         }
-        void remove( detail::orderable& e )
+        void remove( detail::sequenceable& o )
         {
-            elements_.erase( std::remove( elements_.begin(),
-                elements_.end(), &e ), elements_.end() );
+            orderables_.erase( std::remove( orderables_.begin(),
+                orderables_.end(), &o ), orderables_.end() );
             called_.erase( std::remove( called_.begin(),
-                called_.end(), &e ), called_.end() );
+                called_.end(), &o ), called_.end() );
         }
 
-        bool is_valid( const detail::orderable& e ) const
+        bool is_valid( const detail::sequenceable& o ) const
         {
-            return std::find( called_.begin(), called_.end(), &e )
+            return std::find( called_.begin(), called_.end(), &o )
                 == called_.end();
         }
 
-        void call( const detail::orderable& e )
+        void call( const detail::sequenceable& o )
         {
-            elements_it it =
-                std::find( elements_.begin(), elements_.end(), &e );
-            if( it != elements_.end() )
+            orderables_it it =
+                std::find( orderables_.begin(), orderables_.end(), &o );
+            if( it != orderables_.end() )
             {
-                std::copy( elements_.begin(), it,
+                std::copy( orderables_.begin(), it,
                     std::back_inserter( called_ ) );
-                elements_.erase( elements_.begin(), it );
+                orderables_.erase( orderables_.begin(), it );
             }
         }
 
     private:
-        typedef std::vector< detail::orderable* > elements_type;
-        typedef elements_type::iterator elements_it;
+        typedef std::vector< detail::sequenceable* > orderables_type;
+        typedef orderables_type::iterator orderables_it;
 
-        elements_type elements_;
-        elements_type called_;
+        orderables_type orderables_, called_;
     };
 }
 
diff --git a/src/libraries/turtle/orderable.hpp b/src/libraries/turtle/sequenceable.hpp
similarity index 58%
rename from src/libraries/turtle/orderable.hpp
rename to src/libraries/turtle/sequenceable.hpp
index 1404225..694ce94 100644
--- a/src/libraries/turtle/orderable.hpp
+++ b/src/libraries/turtle/sequenceable.hpp
@@ -6,8 +6,8 @@
 //  http://www.boost.org/LICENSE_1_0.txt)
 //
 
-#ifndef MOCK_ORDERABLE_HPP_INCLUDED
-#define MOCK_ORDERABLE_HPP_INCLUDED
+#ifndef MOCK_SEQUENCEABLE_HPP_INCLUDED
+#define MOCK_SEQUENCEABLE_HPP_INCLUDED
 
 namespace mock
 {
@@ -15,11 +15,11 @@ namespace mock
 
 namespace detail
 {
-    class orderable
+    class sequenceable
     {
     public:
-        orderable() {}
-        virtual ~orderable() {}
+        sequenceable() {}
+        virtual ~sequenceable() {}
 
         virtual void remove( sequence& s ) = 0;
     };
@@ -27,4 +27,4 @@ namespace detail
 
 }
 
-#endif // #ifndef MOCK_ORDERABLE_HPP_INCLUDED
+#endif // #ifndef MOCK_SEQUENCEABLE_HPP_INCLUDED