diff --git a/lib/std/libc/os/posix.c3 b/lib/std/libc/os/posix.c3
index 0146c662e..c3fecc2f1 100644
--- a/lib/std/libc/os/posix.c3
+++ b/lib/std/libc/os/posix.c3
@@ -62,17 +62,18 @@ module libc::termios @if(env::LIBC &&& env::POSIX);
 distinct Cc = char;
 distinct Speed = CUInt;
 distinct Tcflags = CUInt;
+distinct Tcactions = CInt;
 
-const Tcflags TCOOFF = 0;
-const Tcflags TCOON = 1;
-const Tcflags TCIOFF = 2;
-const Tcflags TCION = 3;
-const Tcflags TCIFLUSH = 0;
-const Tcflags TCOFLUSH = 1;
-const Tcflags TCIOFLUSH = 2;
-const Tcflags TCSANOW = 0;
-const Tcflags TCSADRAIN = 1;
-const Tcflags TCSAFLUSH = 2;
+const Tcactions TCOOFF = 0;
+const Tcactions TCOON = 1;
+const Tcactions TCIOFF = 2;
+const Tcactions TCION = 3;
+const Tcactions TCIFLUSH = 0;
+const Tcactions TCOFLUSH = 1;
+const Tcactions TCIOFLUSH = 2;
+const Tcactions TCSANOW = 0;
+const Tcactions TCSADRAIN = 1;
+const Tcactions TCSAFLUSH = 2;
 const Speed B0 = 0000000;
 const Speed B50 = 0000001;
 const Speed B75 = 0000002;
@@ -105,72 +106,72 @@ const Speed B3000000 = 0010015;
 const Speed B3500000 = 0010016;
 const Speed B4000000 = 0010017;
 const Speed MAX_BAUD = B4000000;
-const CInt VINTR = 0;
-const CInt VQUIT = 1;
-const CInt VERASE = 2;
-const CInt VKILL = 3;
-const CInt VEOF = 4;
-const CInt VTIME = 5;
-const CInt VMIN = 6;
-const CInt VSWTC = 7;
-const CInt VSTART = 8;
-const CInt VSTOP = 9;
-const CInt VSUSP = 10;
-const CInt VEOL = 11;
-const CInt VREPRINT = 12;
-const CInt VDISCARD = 13;
-const CInt VWERASE = 14;
-const CInt VLNEXT = 15;
-const CInt VEOL2 = 16;
-const CInt ISIG = 0000001;
-const CInt ICANON = 0000002;
-const CInt ECHO = 0000010;
-const CInt ECHOE = 0000020;
-const CInt ECHOK = 0000040;
-const CInt ECHONL = 0000100;
-const CInt NOFLSH = 0000200;
-const CInt TOSTOP = 0000400;
-const CInt IEXTEN = 0100000;
-const CInt CSIZE = 0000060;
-const CInt CS5 = 0000000;
-const CInt CS6 = 0000020;
-const CInt CS7 = 0000040;
-const CInt CS8 = 0000060;
-const CInt CSTOPB = 0000100;
-const CInt CREAD = 0000200;
-const CInt PARENB = 0000400;
-const CInt PARODD = 0001000;
-const CInt HUPCL = 0002000;
-const CInt CLOCAL = 0004000;
-const CInt OPOST = 0000001;
-const CInt OLCUC = 0000002;
-const CInt ONLCR = 0000004;
-const CInt OCRNL = 0000010;
-const CInt ONOCR = 0000020;
-const CInt ONLRET = 0000040;
-const CInt OFILL = 0000100;
-const CInt OFDEL = 0000200;
-const CInt VTDLY = 0040000;
-const CInt VT0 = 0000000;
-const CInt VT1 = 0040000;
-const CInt IGNBRK = 0000001;
-const CInt BRKINT = 0000002;
-const CInt IGNPAR = 0000004;
-const CInt PARMRK = 0000010;
-const CInt INPCK = 0000020;
-const CInt ISTRIP = 0000040;
-const CInt INLCR = 0000100;
-const CInt IGNCR = 0000200;
-const CInt ICRNL = 0000400;
-const CInt IUCLC = 0001000;
-const CInt IXON = 0002000;
-const CInt IXANY = 0004000;
-const CInt IXOFF = 0010000;
-const CInt IMAXBEL = 0020000;
-const CInt IUTF8 = 0040000;
+const Tcflags VINTR = 0;
+const Tcflags VQUIT = 1;
+const Tcflags VERASE = 2;
+const Tcflags VKILL = 3;
+const Tcflags VEOF = 4;
+const Tcflags VTIME = 5;
+const Tcflags VMIN = 6;
+const Tcflags VSWTC = 7;
+const Tcflags VSTART = 8;
+const Tcflags VSTOP = 9;
+const Tcflags VSUSP = 10;
+const Tcflags VEOL = 11;
+const Tcflags VREPRINT = 12;
+const Tcflags VDISCARD = 13;
+const Tcflags VWERASE = 14;
+const Tcflags VLNEXT = 15;
+const Tcflags VEOL2 = 16;
+const Tcflags ISIG = 0000001;
+const Tcflags ICANON = 0000002;
+const Tcflags ECHO = 0000010;
+const Tcflags ECHOE = 0000020;
+const Tcflags ECHOK = 0000040;
+const Tcflags ECHONL = 0000100;
+const Tcflags NOFLSH = 0000200;
+const Tcflags TOSTOP = 0000400;
+const Tcflags IEXTEN = 0100000;
+const Tcflags CSIZE = 0000060;
+const Tcflags CS5 = 0000000;
+const Tcflags CS6 = 0000020;
+const Tcflags CS7 = 0000040;
+const Tcflags CS8 = 0000060;
+const Tcflags CSTOPB = 0000100;
+const Tcflags CREAD = 0000200;
+const Tcflags PARENB = 0000400;
+const Tcflags PARODD = 0001000;
+const Tcflags HUPCL = 0002000;
+const Tcflags CLOCAL = 0004000;
+const Tcflags OPOST = 0000001;
+const Tcflags OLCUC = 0000002;
+const Tcflags ONLCR = 0000004;
+const Tcflags OCRNL = 0000010;
+const Tcflags ONOCR = 0000020;
+const Tcflags ONLRET = 0000040;
+const Tcflags OFILL = 0000100;
+const Tcflags OFDEL = 0000200;
+const Tcflags VTDLY = 0040000;
+const Tcflags VT0 = 0000000;
+const Tcflags VT1 = 0040000;
+const Tcflags IGNBRK = 0000001;
+const Tcflags BRKINT = 0000002;
+const Tcflags IGNPAR = 0000004;
+const Tcflags PARMRK = 0000010;
+const Tcflags INPCK = 0000020;
+const Tcflags ISTRIP = 0000040;
+const Tcflags INLCR = 0000100;
+const Tcflags IGNCR = 0000200;
+const Tcflags ICRNL = 0000400;
+const Tcflags IUCLC = 0001000;
+const Tcflags IXON = 0002000;
+const Tcflags IXANY = 0004000;
+const Tcflags IXOFF = 0010000;
+const Tcflags IMAXBEL = 0020000;
+const Tcflags IUTF8 = 0040000;
 
 extern fn CInt tcgetattr(Fd fd, Termios* self);
-extern fn CInt tcsetattr(Fd fd, CInt optional_actions, Termios* self);
+extern fn CInt tcsetattr(Fd fd, Tcactions optional_actions, Termios* self);
 extern fn CInt tcsendbreak(Fd fd, CInt duration);
 extern fn CInt tcdrain(Fd fd);
 extern fn CInt tcflush(Fd fd, CInt queue_selector);
diff --git a/lib/std/libc/termios.c3 b/lib/std/libc/termios.c3
index 446b51364..de33e4875 100644
--- a/lib/std/libc/termios.c3
+++ b/lib/std/libc/termios.c3
@@ -9,7 +9,7 @@ fn Speed Termios.getISpeed(Termios* self) => cfgetispeed(self);
 fn int Termios.setOSpeed(Termios* self, Speed speed) => cfsetospeed(self, speed);
 fn int Termios.setISpeed(Termios* self, Speed speed) => cfsetispeed(self, speed);
 fn int Termios.getAttr(Termios* self, Fd fd) => tcgetattr(fd, self);
-fn int Termios.setAttr(Termios* self, Fd fd, int optional_actions) => tcsetattr(fd, optional_actions, self);
+fn int Termios.setAttr(Termios* self, Fd fd, Tcactions optional_actions) => tcsetattr(fd, optional_actions, self);
 
 module libc::termios @if(!env::LIBC ||| !env::POSIX);