diff --git a/chardev/char.c b/chardev/char.c
index 0169d8dde4..b005df3ccf 100644
--- a/chardev/char.c
+++ b/chardev/char.c
@@ -193,7 +193,7 @@ int qemu_chr_be_can_write(Chardev *s)
     return be->chr_can_read(be->opaque);
 }
 
-void qemu_chr_be_write_impl(Chardev *s, uint8_t *buf, int len)
+void qemu_chr_be_write_impl(Chardev *s, const uint8_t *buf, int len)
 {
     CharBackend *be = s->be;
 
@@ -202,7 +202,7 @@ void qemu_chr_be_write_impl(Chardev *s, uint8_t *buf, int len)
     }
 }
 
-void qemu_chr_be_write(Chardev *s, uint8_t *buf, int len)
+void qemu_chr_be_write(Chardev *s, const uint8_t *buf, int len)
 {
     if (qemu_chr_replay(s)) {
         if (replay_mode == REPLAY_MODE_PLAY) {
diff --git a/include/chardev/char.h b/include/chardev/char.h
index a319b5fdff..44cd82e405 100644
--- a/include/chardev/char.h
+++ b/include/chardev/char.h
@@ -186,7 +186,7 @@ int qemu_chr_be_can_write(Chardev *s);
  * the caller should call @qemu_chr_be_can_write to determine how much data
  * the front end can currently accept.
  */
-void qemu_chr_be_write(Chardev *s, uint8_t *buf, int len);
+void qemu_chr_be_write(Chardev *s, const uint8_t *buf, int len);
 
 /**
  * qemu_chr_be_write_impl:
@@ -195,7 +195,7 @@ void qemu_chr_be_write(Chardev *s, uint8_t *buf, int len);
  *
  * Implementation of back end writing. Used by replay module.
  */
-void qemu_chr_be_write_impl(Chardev *s, uint8_t *buf, int len);
+void qemu_chr_be_write_impl(Chardev *s, const uint8_t *buf, int len);
 
 /**
  * qemu_chr_be_update_read_handlers:
diff --git a/include/sysemu/replay.h b/include/sysemu/replay.h
index 73dee9ccdf..7ec0882b50 100644
--- a/include/sysemu/replay.h
+++ b/include/sysemu/replay.h
@@ -198,7 +198,7 @@ uint64_t blkreplay_next_id(void);
 /*! Registers char driver to save it's events */
 void replay_register_char_driver(struct Chardev *chr);
 /*! Saves write to char device event to the log */
-void replay_chr_be_write(struct Chardev *s, uint8_t *buf, int len);
+void replay_chr_be_write(struct Chardev *s, const uint8_t *buf, int len);
 /*! Writes char write return value to the replay log. */
 void replay_char_write_event_save(int res, int offset);
 /*! Reads char write return value from the replay log. */
diff --git a/replay/replay-char.c b/replay/replay-char.c
index d2025948cf..a31aded032 100644
--- a/replay/replay-char.c
+++ b/replay/replay-char.c
@@ -48,7 +48,7 @@ void replay_register_char_driver(Chardev *chr)
     char_drivers[drivers_count++] = chr;
 }
 
-void replay_chr_be_write(Chardev *s, uint8_t *buf, int len)
+void replay_chr_be_write(Chardev *s, const uint8_t *buf, int len)
 {
     CharEvent *event = g_new0(CharEvent, 1);
 
diff --git a/stubs/replay-tools.c b/stubs/replay-tools.c
index f2e72bb225..3e8ca3212d 100644
--- a/stubs/replay-tools.c
+++ b/stubs/replay-tools.c
@@ -53,7 +53,7 @@ void replay_register_char_driver(struct Chardev *chr)
 {
 }
 
-void replay_chr_be_write(struct Chardev *s, uint8_t *buf, int len)
+void replay_chr_be_write(struct Chardev *s, const uint8_t *buf, int len)
 {
     abort();
 }