diff --git a/CHANGELOG.md b/CHANGELOG.md
index 913e8166..7c6f4040 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,6 +3,7 @@ Version 51
 * Fix operator<< for header
 * Tidy up file_body
 * Fix file_body::get() not setting the more flag correctly
+* Use BOOST_FALLTHROUGH
 
 API Changes:
 
diff --git a/include/beast/http/impl/basic_parser.ipp b/include/beast/http/impl/basic_parser.ipp
index 00eb3a55..343760a4 100644
--- a/include/beast/http/impl/basic_parser.ipp
+++ b/include/beast/http/impl/basic_parser.ipp
@@ -14,6 +14,7 @@
 #include <beast/http/error.hpp>
 #include <beast/http/rfc7230.hpp>
 #include <boost/asio/buffer.hpp>
+#include <boost/config.hpp>
 #include <algorithm>
 #include <utility>
 
@@ -114,7 +115,7 @@ loop:
             return 0;
         }
         state_ = state::header;
-        // [[fallthrough]]
+        BOOST_FALLTHROUGH;
 
     case state::header:
         parse_header(p, n, ec);
@@ -127,7 +128,7 @@ loop:
         if(ec)
             goto done;
         state_ = state::body;
-        // [[fallthrough]]
+        BOOST_FALLTHROUGH;
 
     case state::body:
         parse_body(p, n, ec);
@@ -140,7 +141,7 @@ loop:
         if(ec)
             goto done;
         state_ = state::body_to_eof;
-        // [[fallthrough]]
+        BOOST_FALLTHROUGH;
 
     case state::body_to_eof:
         parse_body_to_eof(p, n, ec);
@@ -153,7 +154,7 @@ loop:
         if(ec)
             goto done;
         state_ = state::chunk_header;
-        // [[fallthrough]]
+        BOOST_FALLTHROUGH;
 
     case state::chunk_header:
         parse_chunk_header(p, n, ec);
diff --git a/include/beast/http/impl/read.ipp b/include/beast/http/impl/read.ipp
index cc3fe2da..06f354aa 100644
--- a/include/beast/http/impl/read.ipp
+++ b/include/beast/http/impl/read.ipp
@@ -20,6 +20,7 @@
 #include <boost/asio/handler_continuation_hook.hpp>
 #include <boost/asio/handler_invoke_hook.hpp>
 #include <boost/assert.hpp>
+#include <boost/config.hpp>
 #include <boost/optional.hpp>
 #include <boost/throw_exception.hpp>
 
@@ -139,7 +140,7 @@ operator()(error_code ec, std::size_t bytes_transferred)
         if(! ec || ec != http::error::need_more)
             goto do_upcall;
         ec = {};
-        // [[fallthrough]]
+        BOOST_FALLTHROUGH;
 
     do_read:
         try
@@ -277,7 +278,7 @@ operator()(error_code ec)
                 bind_handler(std::move(*this), ec));
         }
         state_ = 2;
-        // [[fallthrough]]
+        BOOST_FALLTHROUGH;
 
     do_read:
         return async_read_some(
diff --git a/include/beast/http/impl/serializer.ipp b/include/beast/http/impl/serializer.ipp
index 79df9268..0a226864 100644
--- a/include/beast/http/impl/serializer.ipp
+++ b/include/beast/http/impl/serializer.ipp
@@ -11,6 +11,7 @@
 #include <beast/http/error.hpp>
 #include <beast/http/status.hpp>
 #include <boost/assert.hpp>
+#include <boost/config.hpp>
 #include <ostream>
 
 namespace beast {
@@ -63,7 +64,7 @@ get(error_code& ec, Visit&& visit)
         if(m_.has_chunked())
             goto go_init_c;
         s_ = do_init;
-        // [[fallthrough]]
+        BOOST_FALLTHROUGH;
     }
 
     case do_init:
@@ -89,7 +90,7 @@ get(error_code& ec, Visit&& visit)
             frd_->get(),
             result->first};
         s_ = do_header;
-        // [[fallthrough]]
+        BOOST_FALLTHROUGH;
     }
 
     case do_header:
@@ -110,7 +111,7 @@ get(error_code& ec, Visit&& visit)
         if(ec)
             return;
         s_ = do_body + 1;
-        // [[fallthrough]]
+        BOOST_FALLTHROUGH;
 
     case do_body + 1:
     {
@@ -122,7 +123,7 @@ get(error_code& ec, Visit&& visit)
         more_ = result->second;
         v_ = cb1_t{result->first};
         s_ = do_body + 2;
-        // [[fallthrough]]
+        BOOST_FALLTHROUGH;
     }
 
     case do_body + 2:
@@ -167,7 +168,7 @@ get(error_code& ec, Visit&& visit)
             result->first,
             detail::chunk_crlf()};
         s_ = do_header_c;
-        // [[fallthrough]]
+        BOOST_FALLTHROUGH;
     }
 
     case do_header_c:
@@ -188,7 +189,7 @@ get(error_code& ec, Visit&& visit)
         if(ec)
             return;
         s_ = do_body_c + 1;
-        // [[fallthrough]]
+        BOOST_FALLTHROUGH;
 
     case do_body_c + 1:
     {
@@ -213,7 +214,7 @@ get(error_code& ec, Visit&& visit)
             result->first,
             detail::chunk_crlf()};
         s_ = do_body_c + 2;
-        // [[fallthrough]]
+        BOOST_FALLTHROUGH;
     }
 
     case do_body_c + 2:
@@ -235,7 +236,7 @@ get(error_code& ec, Visit&& visit)
             }(),
             detail::chunk_crlf()};
         s_ = do_final_c + 1;
-        // [[fallthrough]]
+        BOOST_FALLTHROUGH;
 
     case do_final_c + 1:
         visit(ec, boost::get<ch2_t>(v_));
diff --git a/include/beast/http/impl/status.ipp b/include/beast/http/impl/status.ipp
index 5a7d579b..6058247a 100644
--- a/include/beast/http/impl/status.ipp
+++ b/include/beast/http/impl/status.ipp
@@ -8,6 +8,7 @@
 #ifndef BEAST_HTTP_IMPL_STATUS_IPP
 #define BEAST_HTTP_IMPL_STATUS_IPP
 
+#include <boost/config.hpp>
 #include <boost/throw_exception.hpp>
 
 namespace beast {
@@ -24,7 +25,7 @@ int_to_status(int v)
     case status::continue_:
     case status::switching_protocols:
     case status::processing:
-        // [[fallthrough]]
+        BOOST_FALLTHROUGH;
 
     // 2xx
     case status::ok:
@@ -37,7 +38,7 @@ int_to_status(int v)
     case status::multi_status:
     case status::already_reported:
     case status::im_used:
-        // [[fallthrough]]
+        BOOST_FALLTHROUGH;
 
     // 3xx
     case status::multiple_choices:
@@ -48,7 +49,7 @@ int_to_status(int v)
     case status::use_proxy:
     case status::temporary_redirect:
     case status::permanent_redirect:
-        // [[fallthrough]]
+        BOOST_FALLTHROUGH;
 
     // 4xx
     case status::bad_request:
@@ -80,7 +81,7 @@ int_to_status(int v)
     case status::connection_closed_without_response:
     case status::unavailable_for_legal_reasons:
     case status::client_closed_request:
-        // [[fallthrough]]
+        BOOST_FALLTHROUGH;
 
     // 5xx
     case status::internal_server_error:
diff --git a/include/beast/http/impl/verb.ipp b/include/beast/http/impl/verb.ipp
index f72e1089..a898d718 100644
--- a/include/beast/http/impl/verb.ipp
+++ b/include/beast/http/impl/verb.ipp
@@ -8,6 +8,7 @@
 #ifndef BEAST_HTTP_IMPL_VERB_IPP
 #define BEAST_HTTP_IMPL_VERB_IPP
 
+#include <boost/config.hpp>
 #include <boost/throw_exception.hpp>
 #include <stdexcept>
 
@@ -155,7 +156,7 @@ string_to_verb(string_view v)
                 return verb::connect;
             if(eq(v, "PY"))
                 return verb::copy;
-            // [[fallthrough]]
+            BOOST_FALLTHROUGH;
 
         default:
             break;
@@ -216,7 +217,7 @@ string_to_verb(string_view v)
         case 'O':
             if(eq(v, "VE"))
                 return verb::move;
-            // [[fallthrough]]
+            BOOST_FALLTHROUGH;
 
         default:
             break;
@@ -260,7 +261,7 @@ string_to_verb(string_view v)
                 return verb::purge;
             if(eq(v, "T"))
                 return verb::put;
-            // [[fallthrough]]
+            BOOST_FALLTHROUGH;
 
         default:
             break;
diff --git a/include/beast/http/impl/write.ipp b/include/beast/http/impl/write.ipp
index 5742eed2..a71cf2ca 100644
--- a/include/beast/http/impl/write.ipp
+++ b/include/beast/http/impl/write.ipp
@@ -18,6 +18,7 @@
 #include <boost/asio/handler_continuation_hook.hpp>
 #include <boost/asio/handler_invoke_hook.hpp>
 #include <boost/asio/write.hpp>
+#include <boost/config.hpp>
 #include <boost/optional.hpp>
 #include <boost/throw_exception.hpp>
 #include <ostream>
@@ -317,7 +318,7 @@ operator()(error_code ec,
 
     case 2:
         state_ = 3;
-        // [[fallthrough]]
+        BOOST_FALLTHROUGH;
 
     case 3:
     {
diff --git a/include/beast/websocket/impl/close.ipp b/include/beast/websocket/impl/close.ipp
index e6ac1083..43d68ef7 100644
--- a/include/beast/websocket/impl/close.ipp
+++ b/include/beast/websocket/impl/close.ipp
@@ -14,6 +14,7 @@
 #include <boost/asio/handler_alloc_hook.hpp>
 #include <boost/asio/handler_continuation_hook.hpp>
 #include <boost/asio/handler_invoke_hook.hpp>
+#include <boost/config.hpp>
 #include <boost/throw_exception.hpp>
 #include <memory>
 
@@ -153,7 +154,7 @@ operator()(error_code ec, bool again)
                 return;
             }
             d.ws.wr_block_ = &d;
-            // [[fallthrough]]
+            BOOST_FALLTHROUGH;
 
         case 1:
             // send close frame
diff --git a/include/beast/websocket/impl/ping.ipp b/include/beast/websocket/impl/ping.ipp
index 5083cb9e..598953f0 100644
--- a/include/beast/websocket/impl/ping.ipp
+++ b/include/beast/websocket/impl/ping.ipp
@@ -15,6 +15,7 @@
 #include <boost/asio/handler_alloc_hook.hpp>
 #include <boost/asio/handler_continuation_hook.hpp>
 #include <boost/asio/handler_invoke_hook.hpp>
+#include <boost/config.hpp>
 #include <boost/throw_exception.hpp>
 #include <memory>
 
@@ -152,7 +153,7 @@ operator()(error_code ec, bool again)
                 return;
             }
             d.ws.wr_block_ = &d;
-            // [[fallthrough]]
+            BOOST_FALLTHROUGH;
 
         case 1:
             // send ping frame
diff --git a/include/beast/websocket/impl/read.ipp b/include/beast/websocket/impl/read.ipp
index ed1f157d..eba9bab4 100644
--- a/include/beast/websocket/impl/read.ipp
+++ b/include/beast/websocket/impl/read.ipp
@@ -18,6 +18,7 @@
 #include <boost/asio/handler_continuation_hook.hpp>
 #include <boost/asio/handler_invoke_hook.hpp>
 #include <boost/assert.hpp>
+#include <boost/config.hpp>
 #include <boost/optional.hpp>
 #include <boost/throw_exception.hpp>
 #include <limits>
@@ -522,7 +523,7 @@ operator()(error_code ec,
                     ec = boost::asio::error::operation_aborted;
                     goto upcall;
                 }
-                // [[fallthrough]]
+                BOOST_FALLTHROUGH;
 
             //------------------------------------------------------------------
 
diff --git a/include/beast/websocket/impl/write.ipp b/include/beast/websocket/impl/write.ipp
index a3dbd242..36a4a971 100644
--- a/include/beast/websocket/impl/write.ipp
+++ b/include/beast/websocket/impl/write.ipp
@@ -21,6 +21,7 @@
 #include <boost/asio/handler_continuation_hook.hpp>
 #include <boost/asio/handler_invoke_hook.hpp>
 #include <boost/assert.hpp>
+#include <boost/config.hpp>
 #include <boost/throw_exception.hpp>
 #include <algorithm>
 #include <memory>
@@ -230,7 +231,7 @@ operator()(error_code ec,
         case do_nomask_nofrag:
             BOOST_ASSERT(! d.ws.wr_block_);
             d.ws.wr_block_ = &d;
-            // [[fallthrough]]
+            BOOST_FALLTHROUGH;
 
         case do_nomask_nofrag + 1:
         {
@@ -253,7 +254,7 @@ operator()(error_code ec,
         case do_nomask_frag:
             BOOST_ASSERT(! d.ws.wr_block_);
             d.ws.wr_block_ = &d;
-            // [[fallthrough]]
+            BOOST_FALLTHROUGH;
 
         case do_nomask_frag + 1:
         {
@@ -301,7 +302,7 @@ operator()(error_code ec,
         case do_mask_nofrag:
             BOOST_ASSERT(! d.ws.wr_block_);
             d.ws.wr_block_ = &d;
-            // [[fallthrough]]
+            BOOST_FALLTHROUGH;
 
         case do_mask_nofrag + 1:
         {
@@ -353,7 +354,7 @@ operator()(error_code ec,
         case do_mask_frag:
             BOOST_ASSERT(! d.ws.wr_block_);
             d.ws.wr_block_ = &d;
-            // [[fallthrough]]
+            BOOST_FALLTHROUGH;
 
         case do_mask_frag + 1:
         {
@@ -406,7 +407,7 @@ operator()(error_code ec,
         case do_deflate:
             BOOST_ASSERT(! d.ws.wr_block_);
             d.ws.wr_block_ = &d;
-            // [[fallthrough]]
+            BOOST_FALLTHROUGH;
 
         case do_deflate + 1:
         {
diff --git a/test/websocket/ssl/websocket_async_ssl_echo_server.hpp b/test/websocket/ssl/websocket_async_ssl_echo_server.hpp
index 6a2f0b50..9a5bb4d5 100644
--- a/test/websocket/ssl/websocket_async_ssl_echo_server.hpp
+++ b/test/websocket/ssl/websocket_async_ssl_echo_server.hpp
@@ -12,6 +12,7 @@
 #include <beast/websocket/ssl.hpp>
 #include <beast/websocket/stream.hpp>
 #include <boost/asio/ssl.hpp>
+#include <boost/config.hpp>
 #include <boost/lexical_cast.hpp>
 #include <boost/optional.hpp>
 #include <atomic>
@@ -234,7 +235,7 @@ private:
             case 2:
                 if(ec)
                     return fail("async_handshake", ec);
-                // [[fallthrough]]
+                BOOST_FALLTHROUGH;
 
             // WebSocket read
             case 3: