diff --git a/pty_linux.go b/pty_linux.go
index 6e5a042..326899b 100644
--- a/pty_linux.go
+++ b/pty_linux.go
@@ -8,8 +8,8 @@ import (
 )
 
 var (
-	ioctl_TIOCGPTN   = _IOR('T', 0x30, unsafe.Sizeof(_C_uint(0))) /* Get Pty Number (of pty-mux device) */
-	ioctl_TIOCSPTLCK = _IOW('T', 0x31, unsafe.Sizeof(_C_int(0)))  /* Lock/unlock Pty */
+	ioctl_TIOCGPTN   = uintptr(syscall.TIOCGPTN)   /* Get Pty Number (of pty-mux device) */
+	ioctl_TIOCSPTLCK = uintptr(syscall.TIOCSPTLCK) /* Lock/unlock Pty */
 )
 
 func open() (pty, tty *os.File, err error) {