diff --git a/include/boost/detail/bad_weak_ptr.hpp b/include/boost/detail/bad_weak_ptr.hpp
new file mode 100644
index 0000000..a08d7b1
--- /dev/null
+++ b/include/boost/detail/bad_weak_ptr.hpp
@@ -0,0 +1,59 @@
+#ifndef BOOST_BAD_WEAK_PTR_HPP_INCLUDED
+#define BOOST_BAD_WEAK_PTR_HPP_INCLUDED
+
+// MS compatible compilers support #pragma once
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1020)
+# pragma once
+#endif
+
+//
+//  detail/bad_weak_ptr.hpp
+//
+//  Copyright (c) 2001, 2002, 2003 Peter Dimov and Multi Media Ltd.
+//
+// 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 <exception>
+
+#ifdef __BORLANDC__
+# pragma warn -8026     // Functions with excep. spec. are not expanded inline
+#endif
+
+namespace boost
+{
+
+// The standard library that comes with Borland C++ 5.5.1, 5.6.4
+// defines std::exception and its members as having C calling
+// convention (-pc). When the definition of bad_weak_ptr
+// is compiled with -ps, the compiler issues an error.
+// Hence, the temporary #pragma option -pc below.
+
+#if defined(__BORLANDC__) && __BORLANDC__ <= 0x564
+# pragma option push -pc
+#endif
+
+class bad_weak_ptr: public std::exception
+{
+public:
+
+    virtual char const * what() const throw()
+    {
+        return "boost::bad_weak_ptr";
+    }
+};
+
+#if defined(__BORLANDC__) && __BORLANDC__ <= 0x564
+# pragma option pop
+#endif
+
+} // namespace boost
+
+#ifdef __BORLANDC__
+# pragma warn .8026     // Functions with excep. spec. are not expanded inline
+#endif
+
+#endif  // #ifndef BOOST_BAD_WEAK_PTR_HPP_INCLUDED
diff --git a/include/boost/detail/shared_count.hpp b/include/boost/detail/shared_count.hpp
index cc50165..afc4e78 100644
--- a/include/boost/detail/shared_count.hpp
+++ b/include/boost/detail/shared_count.hpp
@@ -11,6 +11,7 @@
 //  detail/shared_count.hpp
 //
 //  Copyright (c) 2001, 2002, 2003 Peter Dimov and Multi Media Ltd.
+//  Copyright 2004-2005 Peter Dimov
 //
 // Distributed under the Boost Software License, Version 1.0. (See
 // accompanying file LICENSE_1_0.txt or copy at
@@ -25,7 +26,8 @@
 
 #include <boost/checked_delete.hpp>
 #include <boost/throw_exception.hpp>
-#include <boost/detail/lightweight_mutex.hpp>
+#include <boost/detail/bad_weak_ptr.hpp>
+#include <boost/detail/sp_counted_base.hpp>
 
 #if defined(BOOST_SP_USE_QUICK_ALLOCATOR)
 #include <boost/detail/quick_allocator.hpp>
@@ -33,13 +35,11 @@
 
 #include <memory>           // std::auto_ptr, std::allocator
 #include <functional>       // std::less
-#include <exception>        // std::exception
 #include <new>              // std::bad_alloc
 #include <typeinfo>         // std::type_info in get_deleter
 #include <cstddef>          // std::size_t
 
 #ifdef __BORLANDC__
-# pragma warn -8026     // Functions with excep. spec. are not expanded inline
 # pragma warn -8027     // Functions containing try are not expanded inline
 #endif
 
@@ -57,142 +57,9 @@ void sp_array_destructor_hook(void * px);
 
 #endif
 
-
-// The standard library that comes with Borland C++ 5.5.1, 5.6.4
-// defines std::exception and its members as having C calling
-// convention (-pc). When the definition of bad_weak_ptr
-// is compiled with -ps, the compiler issues an error.
-// Hence, the temporary #pragma option -pc below.
-
-#if defined(__BORLANDC__) && __BORLANDC__ <= 0x564
-# pragma option push -pc
-#endif
-
-class bad_weak_ptr: public std::exception
-{
-public:
-
-    virtual char const * what() const throw()
-    {
-        return "boost::bad_weak_ptr";
-    }
-};
-
-#if defined(__BORLANDC__) && __BORLANDC__ <= 0x564
-# pragma option pop
-#endif
-
 namespace detail
 {
 
-class sp_counted_base
-{
-private:
-
-    typedef detail::lightweight_mutex mutex_type;
-
-public:
-
-    sp_counted_base(): use_count_(1), weak_count_(1)
-    {
-    }
-
-    virtual ~sp_counted_base() // nothrow
-    {
-    }
-
-    // dispose() is called when use_count_ drops to zero, to release
-    // the resources managed by *this.
-
-    virtual void dispose() = 0; // nothrow
-
-    // destruct() is called when weak_count_ drops to zero.
-
-    virtual void destruct() // nothrow
-    {
-        delete this;
-    }
-
-    virtual void * get_deleter(std::type_info const & ti) = 0;
-
-    void add_ref_copy()
-    {
-#if defined(BOOST_HAS_THREADS)
-        mutex_type::scoped_lock lock(mtx_);
-#endif
-        ++use_count_;
-    }
-
-    void add_ref_lock()
-    {
-#if defined(BOOST_HAS_THREADS)
-        mutex_type::scoped_lock lock(mtx_);
-#endif
-        if(use_count_ == 0) boost::throw_exception(boost::bad_weak_ptr());
-        ++use_count_;
-    }
-
-    void release() // nothrow
-    {
-        {
-#if defined(BOOST_HAS_THREADS)
-            mutex_type::scoped_lock lock(mtx_);
-#endif
-            long new_use_count = --use_count_;
-
-            if(new_use_count != 0) return;
-        }
-
-        dispose();
-        weak_release();
-    }
-
-    void weak_add_ref() // nothrow
-    {
-#if defined(BOOST_HAS_THREADS)
-        mutex_type::scoped_lock lock(mtx_);
-#endif
-        ++weak_count_;
-    }
-
-    void weak_release() // nothrow
-    {
-        long new_weak_count;
-
-        {
-#if defined(BOOST_HAS_THREADS)
-            mutex_type::scoped_lock lock(mtx_);
-#endif
-            new_weak_count = --weak_count_;
-        }
-
-        if(new_weak_count == 0)
-        {
-            destruct();
-        }
-    }
-
-    long use_count() const // nothrow
-    {
-#if defined(BOOST_HAS_THREADS)
-        mutex_type::scoped_lock lock(mtx_);
-#endif
-        return use_count_;
-    }
-
-private:
-
-    sp_counted_base(sp_counted_base const &);
-    sp_counted_base & operator= (sp_counted_base const &);
-
-    long use_count_;        // #shared
-    long weak_count_;       // #weak + (#shared != 0)
-
-#if defined(BOOST_HAS_THREADS) || defined(BOOST_LWM_WIN32)
-    mutable mutex_type mtx_;
-#endif
-};
-
 #if defined(BOOST_SP_ENABLE_DEBUG_HOOKS)
 
 template<class T> void cbi_call_constructor_hook(sp_counted_base * pn, T * px, checked_deleter<T> const &, int)
@@ -535,13 +402,9 @@ inline shared_count::shared_count(weak_count const & r): pi_(r.pi_)
         , id_(shared_count_id)
 #endif
 {
-    if(pi_ != 0)
+    if( pi_ == 0 || !pi_->add_ref_lock() )
     {
-        pi_->add_ref_lock();
-    }
-    else
-    {
-        boost::throw_exception(boost::bad_weak_ptr());
+        boost::throw_exception( boost::bad_weak_ptr() );
     }
 }
 
@@ -551,7 +414,6 @@ inline shared_count::shared_count(weak_count const & r): pi_(r.pi_)
 
 #ifdef __BORLANDC__
 # pragma warn .8027     // Functions containing try are not expanded inline
-# pragma warn .8026     // Functions with excep. spec. are not expanded inline
 #endif
 
 #endif  // #ifndef BOOST_DETAIL_SHARED_COUNT_HPP_INCLUDED
diff --git a/include/boost/detail/sp_counted_base.hpp b/include/boost/detail/sp_counted_base.hpp
new file mode 100644
index 0000000..194bc1f
--- /dev/null
+++ b/include/boost/detail/sp_counted_base.hpp
@@ -0,0 +1,143 @@
+#ifndef BOOST_DETAIL_SP_COUNTED_BASE_HPP_INCLUDED
+#define BOOST_DETAIL_SP_COUNTED_BASE_HPP_INCLUDED
+
+// MS compatible compilers support #pragma once
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1020)
+# pragma once
+#endif
+
+//
+//  detail/sp_counted_base.hpp
+//
+//  Copyright (c) 2001, 2002, 2003 Peter Dimov and Multi Media Ltd.
+//  Copyright 2004-2005 Peter Dimov
+//
+// 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 <boost/config.hpp>
+#include <boost/detail/lightweight_mutex.hpp>
+
+#include <typeinfo>
+
+namespace boost
+{
+
+namespace detail
+{
+
+class sp_counted_base
+{
+private:
+
+    typedef detail::lightweight_mutex mutex_type;
+
+    sp_counted_base( sp_counted_base const & );
+    sp_counted_base & operator= ( sp_counted_base const & );
+
+    long use_count_;        // #shared
+    long weak_count_;       // #weak + (#shared != 0)
+
+#if defined(BOOST_HAS_THREADS) || defined(BOOST_LWM_WIN32)
+    mutable mutex_type mtx_;
+#endif
+
+public:
+
+    sp_counted_base(): use_count_( 1 ), weak_count_( 1 )
+    {
+    }
+
+    virtual ~sp_counted_base() // nothrow
+    {
+    }
+
+    // dispose() is called when use_count_ drops to zero, to release
+    // the resources managed by *this.
+
+    virtual void dispose() = 0; // nothrow
+
+    // destroy() is called when weak_count_ drops to zero.
+
+    virtual void destroy() // nothrow
+    {
+        delete this;
+    }
+
+    virtual void * get_deleter( std::type_info const & ti ) = 0;
+
+    void add_ref_copy()
+    {
+#if defined(BOOST_HAS_THREADS)
+        mutex_type::scoped_lock lock(mtx_);
+#endif
+        ++use_count_;
+    }
+
+    bool add_ref_lock() // true on success
+    {
+#if defined(BOOST_HAS_THREADS)
+        mutex_type::scoped_lock lock(mtx_);
+#endif
+        if( use_count_ == 0 ) return false;
+        ++use_count_;
+        return true;
+    }
+
+    void release() // nothrow
+    {
+        {
+#if defined(BOOST_HAS_THREADS)
+            mutex_type::scoped_lock lock(mtx_);
+#endif
+            long new_use_count = --use_count_;
+
+            if( new_use_count != 0 ) return;
+        }
+
+        dispose();
+        weak_release();
+    }
+
+    void weak_add_ref() // nothrow
+    {
+#if defined(BOOST_HAS_THREADS)
+        mutex_type::scoped_lock lock(mtx_);
+#endif
+        ++weak_count_;
+    }
+
+    void weak_release() // nothrow
+    {
+        long new_weak_count;
+
+        {
+#if defined(BOOST_HAS_THREADS)
+            mutex_type::scoped_lock lock(mtx_);
+#endif
+            new_weak_count = --weak_count_;
+        }
+
+        if( new_weak_count == 0 )
+        {
+            destroy();
+        }
+    }
+
+    long use_count() const // nothrow
+    {
+#if defined(BOOST_HAS_THREADS)
+        mutex_type::scoped_lock lock(mtx_);
+#endif
+        return use_count_;
+    }
+};
+
+} // namespace detail
+
+} // namespace boost
+
+#endif  // #ifndef BOOST_DETAIL_SP_COUNTED_BASE_HPP_INCLUDED