diff --git a/toxcore/tox.h b/toxcore/tox.h
index 111b2634..f54d113e 100644
--- a/toxcore/tox.h
+++ b/toxcore/tox.h
@@ -314,9 +314,9 @@ void tox_callback_friend_request(Tox *tox, void (*function)(Tox *tox, uint8_t *,
                                  void *userdata);
 
 /* Set the function that will be executed when a message from a friend is received.
- *  Function format is: function(Tox *tox, int friendnumber, uint8_t * message, uint32_t length, void *userdata)
+ *  Function format is: function(Tox *tox, int32_t friendnumber, uint8_t * message, uint32_t length, void *userdata)
  */
-void tox_callback_friend_message(Tox *tox, void (*function)(Tox *tox, int, uint8_t *, uint16_t, void *),
+void tox_callback_friend_message(Tox *tox, void (*function)(Tox *tox, int32_t, uint8_t *, uint16_t, void *),
                                  void *userdata);
 
 /* Set the function that will be executed when an action from a friend is received.