diff --git a/include/boost/detail/sp_counted_base.hpp b/include/boost/detail/sp_counted_base.hpp
index 312893d..6d733d0 100644
--- a/include/boost/detail/sp_counted_base.hpp
+++ b/include/boost/detail/sp_counted_base.hpp
@@ -20,65 +20,46 @@
 #include <boost/config.hpp>
 
 #if defined( BOOST_SP_DISABLE_THREADS )
-
 # include <boost/detail/sp_counted_base_nt.hpp>
 
 #elif defined( BOOST_SP_USE_SPINLOCK )
-
 # include <boost/detail/sp_counted_base_spin.hpp>
 
 #elif defined( BOOST_SP_USE_PTHREADS )
-
 # include <boost/detail/sp_counted_base_pt.hpp>
 
-#elif defined( __GNUC__ ) && ( defined( __i386__ ) || defined( __x86_64__ ) )
+#elif defined( BOOST_DISABLE_THREADS ) && !defined( BOOST_SP_ENABLE_THREADS ) && !defined( BOOST_DISABLE_WIN32 )
+# include <boost/detail/sp_counted_base_nt.hpp>
 
+#elif defined( __GNUC__ ) && ( defined( __i386__ ) || defined( __x86_64__ ) )
 # include <boost/detail/sp_counted_base_gcc_x86.hpp>
 
-//~ #elif defined( __MWERKS__ ) && ( defined( __i386__ ) || defined( __x86_64__ ) )
-
-//~ # include <boost/detail/sp_counted_base_cw_x86.hpp>
-
 #elif defined( __GNUC__ ) && defined( __ia64__ ) && !defined( __INTEL_COMPILER )
-
 # include <boost/detail/sp_counted_base_gcc_ia64.hpp>
 
 #elif defined(__HP_aCC) && defined(__ia64)
-
 # include <boost/detail/sp_counted_base_acc_ia64.hpp>
 
 #elif defined( __MWERKS__ ) && defined( __POWERPC__ )
-
 # include <boost/detail/sp_counted_base_cw_ppc.hpp>
 
 #elif defined( __GNUC__ ) && ( defined( __powerpc__ ) || defined( __ppc__ ) || defined( __ppc ) )
-
 # include <boost/detail/sp_counted_base_gcc_ppc.hpp>
 
-#elif defined(__GNUC__) && ( __GNUC__ * 100 + __GNUC_MINOR__ >= 401 ) && !defined(__arm__) && !defined(__hppa)
-
+#elif defined(__GNUC__) && ( __GNUC__ * 100 + __GNUC_MINOR__ >= 401 ) && !defined( __arm__ ) && !defined( __hppa )
 # include <boost/detail/sp_counted_base_sync.hpp>
 
 #elif defined(__GNUC__) && ( defined( __sparcv8 ) || defined( __sparcv9 ) )
-
 # include <boost/detail/sp_counted_base_gcc_sparc.hpp>
 
 #elif defined( WIN32 ) || defined( _WIN32 ) || defined( __WIN32__ )
-
 # include <boost/detail/sp_counted_base_w32.hpp>
 
 #elif !defined( BOOST_HAS_THREADS )
-
 # include <boost/detail/sp_counted_base_nt.hpp>
 
-#elif defined( BOOST_HAS_PTHREADS )
-
-# include <boost/detail/sp_counted_base_pt.hpp>
-
 #else
-
-// Use #define BOOST_DISABLE_THREADS to avoid the error
-# error Unrecognized threading platform
+# include <boost/detail/sp_counted_base_spin.hpp>
 
 #endif