diff --git a/src/input/rs232.c b/src/input/rs232.c
index 522cf0e..b594db2 100644
--- a/src/input/rs232.c
+++ b/src/input/rs232.c
@@ -86,7 +86,7 @@
 	struct msgb *msg;
 	int written;
 
-	bfd->when &= ~OSMO_FD_WRITE;
+	osmo_fd_write_disable(bfd);
 
 	/* get the next msg for this timeslot */
 	msg = e1inp_tx_ts(e1i_ts, &sign_link);
@@ -207,7 +207,7 @@
 
 static int rs232_want_write(struct e1inp_ts *e1i_ts)
 {
-	e1i_ts->driver.rs232.fd.when |= OSMO_FD_WRITE;
+	osmo_fd_write_enable(&e1i_ts->driver.rs232.fd);
 
 	return 0;
 }