diff --git a/xio-termios.h b/xio-termios.h
index a288a2f..9858aab 100644
--- a/xio-termios.h
+++ b/xio-termios.h
@@ -148,7 +148,7 @@ extern int xiotermiosflag_applyopt(int fd, struct opt *opt);
 extern int xiotermios_value(int fd, int word, tcflag_t mask, tcflag_t value);
 extern int xiotermios_char(int fd, int n, unsigned char c);
 #ifdef HAVE_TERMIOS_ISPEED
-extern int xiotermios_speed(int fd, int n, unsigned int speed);
+extern int xiotermios_speed(int fd, int n, speed_t speed);
 #endif
 extern int xiotermios_spec(int fd, int optcode);
 extern int xiotermios_flush(int fd);