--- boost_1_64_0_vanilla/boost/asio/detail/fenced_block.hpp	2017-04-17 03:22:18.000000000 +0100
+++ boost_1_64_0/boost/asio/detail/fenced_block.hpp	2017-07-13 12:13:21.978227584 +0100
@@ -20,7 +20,7 @@
 #if !defined(BOOST_ASIO_HAS_THREADS) \
   || defined(BOOST_ASIO_DISABLE_FENCED_BLOCK)
 # include <boost/asio/detail/null_fenced_block.hpp>
-#elif defined(BOOST_ASIO_HAS_STD_ATOMIC)
+#elif defined(BOOST_ASIO_HAS_STD_ATOMIC) && (!defined(__GNUC__) || (__GNUC__*100 + __GNUC_MINOR__ > 406))
 # include <boost/asio/detail/std_fenced_block.hpp>
 #elif defined(__MACH__) && defined(__APPLE__)
 # include <boost/asio/detail/macos_fenced_block.hpp>
@@ -51,7 +51,7 @@
 #if !defined(BOOST_ASIO_HAS_THREADS) \
   || defined(BOOST_ASIO_DISABLE_FENCED_BLOCK)
 typedef null_fenced_block fenced_block;
-#elif defined(BOOST_ASIO_HAS_STD_ATOMIC)
+#elif defined(BOOST_ASIO_HAS_STD_ATOMIC) && (!defined(__GNUC__) || (__GNUC__*100 + __GNUC_MINOR__ > 406))
 typedef std_fenced_block fenced_block;
 #elif defined(__MACH__) && defined(__APPLE__)
 typedef macos_fenced_block fenced_block;