Index: detail/system.hpp
===================================================================
--- detail/system.hpp	(revision 78572)
+++ detail/system.hpp	(working copy)
@@ -6,6 +6,8 @@
 #ifndef BOOST_CHRONO_DETAIL_SYSTEM_HPP
 #define BOOST_CHRONO_DETAIL_SYSTEM_HPP
 
+#if !defined BOOST_CHRONO_DONT_PROVIDE_HYBRID_ERROR_HANDLING
+
 #include <boost/version.hpp>
 #include <boost/system/error_code.hpp>
 
@@ -15,7 +17,7 @@
 #define BOOST_CHRONO_SYSTEM_CATEGORY boost::system::system_category()
 #endif
 
-#ifdef BOOST_SYSTEM_NO_DEPRECATED 
+#ifdef BOOST_SYSTEM_NO_DEPRECATED
 #define BOOST_CHRONO_THROWS boost::throws()
 #define BOOST_CHRONO_IS_THROWS(EC) (&EC==&boost::throws())
 #else
@@ -24,3 +26,4 @@
 #endif
 
 #endif
+#endif
Index: config.hpp
===================================================================
--- config.hpp	(revision 78572)
+++ config.hpp	(working copy)
@@ -70,12 +70,8 @@
 # if defined( BOOST_CHRONO_POSIX_API )
 #   define BOOST_CHRONO_HAS_PROCESS_CLOCKS
 #   include <time.h>  //to check for CLOCK_REALTIME and CLOCK_MONOTONIC and _POSIX_THREAD_CPUTIME
-#   if defined(CLOCK_REALTIME)
-#     if defined(CLOCK_MONOTONIC)
-#        define BOOST_CHRONO_HAS_CLOCK_STEADY
-#     endif
-#   else
-#     error <time.h> does not supply CLOCK_REALTIME
+#   if defined(CLOCK_MONOTONIC)
+#      define BOOST_CHRONO_HAS_CLOCK_STEADY
 #   endif
 #   if defined(_POSIX_THREAD_CPUTIME) && !defined(BOOST_DISABLE_THREADS)
 #     define BOOST_CHRONO_HAS_THREAD_CLOCK