diff --git a/src/proto_uxst.c b/src/proto_uxst.c
index 878a10d..965b7cb 100644
--- a/src/proto_uxst.c
+++ b/src/proto_uxst.c
@@ -502,6 +502,14 @@
 		return SF_ERR_INTERNAL;
 	}
 
+	if (master == 1 && (fcntl(fd, F_SETFD, FD_CLOEXEC) == -1)) {
+		ha_alert("Cannot set CLOEXEC on client socket.\n");
+		close(fd);
+		conn->err_code = CO_ER_SOCK_ERR;
+		conn->flags |= CO_FL_ERROR;
+		return SF_ERR_INTERNAL;
+	}
+
 	/* if a send_proxy is there, there are data */
 	data |= conn->send_proxy_ofs;