diff --git a/include/crow/common.h b/include/crow/common.h
index 06f25da6a..e1edb7eca 100644
--- a/include/crow/common.h
+++ b/include/crow/common.h
@@ -205,6 +205,7 @@ namespace crow
         NOT_IMPLEMENTED               = 501,
         BAD_GATEWAY                   = 502,
         SERVICE_UNAVAILABLE           = 503,
+        GATEWAY_TIMEOUT               = 504,
         VARIANT_ALSO_NEGOTIATES       = 506
     };
 
diff --git a/include/crow/http_connection.h b/include/crow/http_connection.h
index 3b902a1e0..f8ce97894 100644
--- a/include/crow/http_connection.h
+++ b/include/crow/http_connection.h
@@ -322,6 +322,7 @@ namespace crow
               {status::NOT_IMPLEMENTED, "HTTP/1.1 501 Not Implemented\r\n"},
               {status::BAD_GATEWAY, "HTTP/1.1 502 Bad Gateway\r\n"},
               {status::SERVICE_UNAVAILABLE, "HTTP/1.1 503 Service Unavailable\r\n"},
+              {status::GATEWAY_TIMEOUT, "HTTP/1.1 504 Gateway Timeout\r\n"},
               {status::VARIANT_ALSO_NEGOTIATES, "HTTP/1.1 506 Variant Also Negotiates\r\n"},
             };