diff --git a/chardev/char-serial.c b/chardev/char-serial.c
index feb52e5..ae548d2 100644
--- a/chardev/char-serial.c
+++ b/chardev/char-serial.c
@@ -139,7 +139,7 @@
 
     tty.c_iflag &= ~(IGNBRK | BRKINT | PARMRK | ISTRIP
                      | INLCR | IGNCR | ICRNL | IXON);
-    tty.c_oflag |= OPOST;
+    tty.c_oflag &= ~OPOST;
     tty.c_lflag &= ~(ECHO | ECHONL | ICANON | IEXTEN | ISIG);
     tty.c_cflag &= ~(CSIZE | PARENB | PARODD | CRTSCTS | CSTOPB);
     switch (data_bits) {
diff --git a/chardev/char-stdio.c b/chardev/char-stdio.c
index 96375f2..d83e60e 100644
--- a/chardev/char-stdio.c
+++ b/chardev/char-stdio.c
@@ -59,7 +59,7 @@
     if (!echo) {
         tty.c_iflag &= ~(IGNBRK | BRKINT | PARMRK | ISTRIP
                          | INLCR | IGNCR | ICRNL | IXON);
-        tty.c_oflag |= OPOST;
+        tty.c_oflag &= ~OPOST;
         tty.c_lflag &= ~(ECHO | ECHONL | ICANON | IEXTEN);
         tty.c_cflag &= ~(CSIZE | PARENB);
         tty.c_cflag |= CS8;