diff --git a/nonblock_bsd.go b/nonblock_bsd.go
index ffe5caf..28fd464 100644
--- a/nonblock_bsd.go
+++ b/nonblock_bsd.go
@@ -26,6 +26,7 @@ import (
 
 // tcSetBufParams is used by the tty driver on UNIX systems to configure the
 // buffering parameters (minimum character count and minimum wait time in msec.)
+// This also waits for output to drain first.
 func tcSetBufParams(fd int, vMin uint8, vTime uint8) error {
 	_ = syscall.SetNonblock(fd, true)
 	tio, err := unix.IoctlGetTermios(fd, unix.TIOCGETA)
@@ -34,7 +35,7 @@ func tcSetBufParams(fd int, vMin uint8, vTime uint8) error {
 	}
 	tio.Cc[unix.VMIN] = vMin
 	tio.Cc[unix.VTIME] = vTime
-	if err = unix.IoctlSetTermios(fd, unix.TIOCSETA, tio); err != nil {
+	if err = unix.IoctlSetTermios(fd, unix.TIOCSETAW, tio); err != nil {
 		return err
 	}
 	return nil
diff --git a/nonblock_unix.go b/nonblock_unix.go
index 768128d..fe31844 100644
--- a/nonblock_unix.go
+++ b/nonblock_unix.go
@@ -24,6 +24,7 @@ import (
 
 // tcSetBufParams is used by the tty driver on UNIX systems to configure the
 // buffering parameters (minimum character count and minimum wait time in msec.)
+// This also waits for output to drain first.
 func tcSetBufParams(fd int, vMin uint8, vTime uint8) error {
 	_ = syscall.SetNonblock(fd, true)
 	tio, err := unix.IoctlGetTermios(fd, unix.TCGETS)
@@ -32,7 +33,7 @@ func tcSetBufParams(fd int, vMin uint8, vTime uint8) error {
 	}
 	tio.Cc[unix.VMIN] = vMin
 	tio.Cc[unix.VTIME] = vTime
-	if err = unix.IoctlSetTermios(fd, unix.TCSETS, tio); err != nil {
+	if err = unix.IoctlSetTermios(fd, unix.TCSETSW, tio); err != nil {
 		return err
 	}
 	return nil