diff --git a/src/fd.c b/src/fd.c
index 17cf52b2d..58d73d4ab 100644
--- a/src/fd.c
+++ b/src/fd.c
@@ -414,6 +414,12 @@ ssize_t fd_write_frag_line(int fd, size_t maxlen, const struct ist pfx[], size_t
 		vec++;
 	}
 
+	if (unlikely(!fdtab[fd].initialized)) {
+		fdtab[fd].initialized = 1;
+		if (!isatty(fd))
+			fcntl(fd, F_SETFL, O_NONBLOCK);
+	}
+
 	HA_SPIN_LOCK(FD_LOCK, &fdtab[fd].lock);
 	sent = writev(fd, iovec, vec);
 	HA_SPIN_UNLOCK(FD_LOCK, &fdtab[fd].lock);
diff --git a/src/log.c b/src/log.c
index b2e6231fa..72602b769 100644
--- a/src/log.c
+++ b/src/log.c
@@ -1504,13 +1504,13 @@ static inline void __do_send_log(struct logsrv *logsrv, int nblogger, char *pid_
 	if (logsrv->addr.ss_family == AF_UNSPEC) {
 		/* the socket's address is a file descriptor */
 		plogfd = (int *)&((struct sockaddr_in *)&logsrv->addr)->sin_addr.s_addr;
-		if (unlikely(!((struct sockaddr_in *)&logsrv->addr)->sin_port)) {
+		if (!fdtab[*plogfd].initialized) {
 			/* FD not yet initialized to non-blocking mode.
 			 * DON'T DO IT ON A TERMINAL!
 			 */
+			fdtab[*plogfd].initialized = 1;
 			if (!isatty(*plogfd))
 				fcntl(*plogfd, F_SETFL, O_NONBLOCK);
-			((struct sockaddr_in *)&logsrv->addr)->sin_port = 1;
 		}
 	}
 	else if (logsrv->addr.ss_family == AF_UNIX)
diff --git a/src/sink.c b/src/sink.c
index ed49062d8..bd06f1ebb 100644
--- a/src/sink.c
+++ b/src/sink.c
@@ -18,8 +18,6 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
  */
 
-#include <fcntl.h>
-#include <unistd.h>
 #include <common/compat.h>
 #include <common/config.h>
 #include <common/ist.h>
@@ -93,11 +91,6 @@ struct sink *sink_new_fd(const char *name, const char *desc, enum sink_fmt fmt,
 		goto end;
 	}
 
-	/* FD not yet initialized to non-blocking mode.
-	 * DON'T DO IT ON A TERMINAL!
-	 */
-	if (!isatty(fd))
-		fcntl(fd, F_SETFL, O_NONBLOCK);
 	sink->type = SINK_TYPE_FD;
 	sink->ctx.fd = fd;
  end: