1 files changed, 6 insertions, 1 deletions

diff --git a/sys/dev/sio/sio.c b/sys/dev/sio/sio.c
index 59bcdad91ed8..066abc806ebf 100644
--- a/sys/dev/sio/sio.c
+++ b/sys/dev/sio/sio.c
@@ -2161,9 +2161,14 @@ comparam(tp, t)
 		 * latencies are reasonable for humans.  Serial comms
 		 * protocols shouldn't expect anything better since modem
 		 * latencies are larger.
+		 *
+		 * We have to set the FIFO trigger point such that we
+		 * don't overflow it accidently if a serial interrupt
+		 * is delayed.  At high speeds, FIFO_RX_HIGH does not
+		 * leave enough slots free.
 		 */
 		com->fifo_image = t->c_ospeed <= 4800
-				  ? FIFO_ENABLE : FIFO_ENABLE | FIFO_RX_HIGH;
+				  ? FIFO_ENABLE : FIFO_ENABLE | FIFO_RX_MEDH;
 #ifdef COM_ESP
 		/*
 		 * The Hayes ESP card needs the fifo DMA mode bit set