diff --git a/include/linux/tty_flip.h b/include/linux/tty_flip.h
index 0c6169f..0976a16 100644
--- a/include/linux/tty_flip.h
+++ b/include/linux/tty_flip.h
@@ -2,8 +2,8 @@
 #define _LINUX_TTY_FLIP_H
 
 extern int tty_buffer_request_room(struct tty_struct *tty, size_t size);
-extern int tty_insert_flip_string(struct tty_struct *tty, unsigned char *chars, size_t size);
-extern int tty_insert_flip_string_flags(struct tty_struct *tty, unsigned char *chars, char *flags, size_t size);
+extern int tty_insert_flip_string(struct tty_struct *tty, const unsigned char *chars, size_t size);
+extern int tty_insert_flip_string_flags(struct tty_struct *tty, const unsigned char *chars, const char *flags, size_t size);
 extern int tty_prepare_flip_string(struct tty_struct *tty, unsigned char **chars, size_t size);
 extern int tty_prepare_flip_string_flags(struct tty_struct *tty, unsigned char **chars, char **flags, size_t size);