diff --git a/toxav/msi.c b/toxav/msi.c
index fda41d0c..dcb7b62a 100644
--- a/toxav/msi.c
+++ b/toxav/msi.c
@@ -774,7 +774,7 @@ static int terminate_call ( MSISession *session, MSICall *call )
     return 0;
 }
 
-static void handle_remote_connection_change(Messenger *messenger, int friend_num, uint8_t status, void *session_p)
+static void handle_remote_connection_change(Messenger *messenger, uint32_t friend_num, uint8_t status, void *session_p)
 {
     (void)messenger;
     MSISession *session = session_p;
@@ -1101,7 +1101,8 @@ static int handle_recv_error ( MSISession *session, MSICall *call, MSIMessage *m
  *
  *
  */
-static void msi_handle_packet ( Messenger *messenger, int source, const uint8_t *data, uint16_t length, void *object )
+static void msi_handle_packet ( Messenger *messenger, uint32_t source, const uint8_t *data, uint16_t length,
+                                void *object )
 {
     LOGGER_DEBUG("Got msi message");
     /* Unused */
diff --git a/toxav/rtp.c b/toxav/rtp.c
index 2af89ebf..63c2cdcb 100644
--- a/toxav/rtp.c
+++ b/toxav/rtp.c
@@ -341,7 +341,7 @@ RTPMessage *msg_parse ( const uint8_t *data, int length )
 /**
  * Callback for networking core.
  */
-int rtp_handle_packet ( Messenger *m, int32_t friendnumber, const uint8_t *data, uint32_t length, void *object )
+int rtp_handle_packet ( Messenger *m, uint32_t friendnumber, const uint8_t *data, uint32_t length, void *object )
 {
     RTPSession *session = object;
     RTPMessage *msg;
diff --git a/toxcore/Messenger.c b/toxcore/Messenger.c
index f566a344..4a173de7 100644
--- a/toxcore/Messenger.c
+++ b/toxcore/Messenger.c
@@ -886,83 +886,83 @@ void m_set_sends_receipts(Messenger *m, int32_t friendnumber, int yesno)
     m->friendlist[friendnumber].receives_read_receipts = yesno;
 }
 
-/* static void (*friend_request)(uint8_t *, uint8_t *, uint16_t); */
 /* Set the function that will be executed when a friend request is received. */
-void m_callback_friendrequest(Messenger *m, void (*function)(Messenger *m, const uint8_t *, const uint8_t *, uint16_t,
+void m_callback_friendrequest(Messenger *m, void (*function)(Messenger *m, const uint8_t *, const uint8_t *, size_t,
                               void *), void *userdata)
 {
-    void (*handle_friendrequest)(void *, const uint8_t *, const uint8_t *, uint16_t, void *) = (void *)function;
+    void (*handle_friendrequest)(void *, const uint8_t *, const uint8_t *, size_t, void *) = (void *)function;
     callback_friendrequest(&(m->fr), handle_friendrequest, m, userdata);
 }
 
 /* Set the function that will be executed when a message from a friend is received. */
-void m_callback_friendmessage(Messenger *m, void (*function)(Messenger *m, int32_t, const uint8_t *, uint16_t, void *),
+void m_callback_friendmessage(Messenger *m, void (*function)(Messenger *m, uint32_t, const uint8_t *, size_t, void *),
                               void *userdata)
 {
     m->friend_message = function;
     m->friend_message_userdata = userdata;
 }
 
-void m_callback_action(Messenger *m, void (*function)(Messenger *m, int32_t, const uint8_t *, uint16_t, void *),
+void m_callback_action(Messenger *m, void (*function)(Messenger *m, uint32_t, const uint8_t *, size_t, void *),
                        void *userdata)
 {
     m->friend_action = function;
     m->friend_action_userdata = userdata;
 }
 
-void m_callback_namechange(Messenger *m, void (*function)(Messenger *m, int32_t, const uint8_t *, uint16_t, void *),
+void m_callback_namechange(Messenger *m, void (*function)(Messenger *m, uint32_t, const uint8_t *, size_t, void *),
                            void *userdata)
 {
     m->friend_namechange = function;
     m->friend_namechange_userdata = userdata;
 }
 
-void m_callback_statusmessage(Messenger *m, void (*function)(Messenger *m, int32_t, const uint8_t *, uint16_t, void *),
+void m_callback_statusmessage(Messenger *m, void (*function)(Messenger *m, uint32_t, const uint8_t *, size_t, void *),
                               void *userdata)
 {
     m->friend_statusmessagechange = function;
     m->friend_statuschange_userdata = userdata;
 }
 
-void m_callback_userstatus(Messenger *m, void (*function)(Messenger *m, int32_t, uint8_t, void *), void *userdata)
+void m_callback_userstatus(Messenger *m, void (*function)(Messenger *m, uint32_t, uint8_t, void *), void *userdata)
 {
     m->friend_userstatuschange = function;
     m->friend_userstatuschange_userdata = userdata;
 }
 
-void m_callback_typingchange(Messenger *m, void(*function)(Messenger *m, int32_t, uint8_t, void *), void *userdata)
+void m_callback_typingchange(Messenger *m, void(*function)(Messenger *m, uint32_t, uint8_t, void *), void *userdata)
 {
     m->friend_typingchange = function;
     m->friend_typingchange_userdata = userdata;
 }
 
-void m_callback_read_receipt(Messenger *m, void (*function)(Messenger *m, int32_t, uint32_t, void *), void *userdata)
+void m_callback_read_receipt(Messenger *m, void (*function)(Messenger *m, uint32_t, uint32_t, void *), void *userdata)
 {
     m->read_receipt = function;
     m->read_receipt_userdata = userdata;
 }
 
-void m_callback_connectionstatus(Messenger *m, void (*function)(Messenger *m, int32_t, uint8_t, void *), void *userdata)
+void m_callback_connectionstatus(Messenger *m, void (*function)(Messenger *m, uint32_t, uint8_t, void *),
+                                 void *userdata)
 {
     m->friend_connectionstatuschange = function;
     m->friend_connectionstatuschange_userdata = userdata;
 }
 
-void m_callback_connectionstatus_internal_av(Messenger *m, void (*function)(Messenger *m, int32_t, uint8_t, void *),
+void m_callback_connectionstatus_internal_av(Messenger *m, void (*function)(Messenger *m, uint32_t, uint8_t, void *),
         void *userdata)
 {
     m->friend_connectionstatuschange_internal = function;
     m->friend_connectionstatuschange_internal_userdata = userdata;
 }
 
-void m_callback_avatar_info(Messenger *m, void (*function)(Messenger *m, int32_t, uint8_t, uint8_t *, void *),
+void m_callback_avatar_info(Messenger *m, void (*function)(Messenger *m, uint32_t, uint8_t, uint8_t *, void *),
                             void *userdata)
 {
     m->avatar_info_recv = function;
     m->avatar_info_recv_userdata = userdata;
 }
 
-void m_callback_avatar_data(Messenger *m, void (*function)(Messenger *m, int32_t, uint8_t, uint8_t *, uint8_t *,
+void m_callback_avatar_data(Messenger *m, void (*function)(Messenger *m, uint32_t, uint8_t, uint8_t *, uint8_t *,
                             uint32_t, void *), void *userdata)
 {
     m->avatar_data_recv = function;
@@ -1027,9 +1027,9 @@ static int write_cryptpacket_id(const Messenger *m, int32_t friendnumber, uint8_
 
 /* Set the callback for group invites.
  *
- *  Function(Messenger *m, int32_t friendnumber, uint8_t *data, uint16_t length)
+ *  Function(Messenger *m, uint32_t friendnumber, uint8_t *data, uint16_t length)
  */
-void m_callback_group_invite(Messenger *m, void (*function)(Messenger *m, int32_t, const uint8_t *, uint16_t))
+void m_callback_group_invite(Messenger *m, void (*function)(Messenger *m, uint32_t, const uint8_t *, uint16_t))
 {
     m->group_invite = function;
 }
@@ -1050,9 +1050,10 @@ int send_group_invite_packet(const Messenger *m, int32_t friendnumber, const uin
 
 /* Set the callback for file send requests.
  *
- *  Function(Tox *tox, int32_t friendnumber, uint8_t filenumber, uint64_t filesize, uint8_t *filename, uint16_t filename_length, void *userdata)
+ *  Function(Tox *tox, uint32_t friendnumber, uint8_t filenumber, uint64_t filesize, uint8_t *filename, uint16_t filename_length, void *userdata)
  */
-void callback_file_sendrequest(Messenger *m, void (*function)(Messenger *m, int32_t, uint8_t, uint64_t, const uint8_t *,
+void callback_file_sendrequest(Messenger *m, void (*function)(Messenger *m, uint32_t, uint8_t, uint64_t,
+                               const uint8_t *,
                                uint16_t, void *), void *userdata)
 {
     m->file_sendrequest = function;
@@ -1061,10 +1062,10 @@ void callback_file_sendrequest(Messenger *m, void (*function)(Messenger *m, int3
 
 /* Set the callback for file control requests.
  *
- *  Function(Tox *tox, int32_t friendnumber, uint8_t send_receive, uint8_t filenumber, uint8_t control_type, uint8_t *data, uint16_t length, void *userdata)
+ *  Function(Tox *tox, uint32_t friendnumber, uint8_t send_receive, uint8_t filenumber, uint8_t control_type, uint8_t *data, uint16_t length, void *userdata)
  *
  */
-void callback_file_control(Messenger *m, void (*function)(Messenger *m, int32_t, uint8_t, uint8_t, uint8_t,
+void callback_file_control(Messenger *m, void (*function)(Messenger *m, uint32_t, uint8_t, uint8_t, uint8_t,
                            const uint8_t *, uint16_t, void *), void *userdata)
 {
     m->file_filecontrol = function;
@@ -1073,10 +1074,11 @@ void callback_file_control(Messenger *m, void (*function)(Messenger *m, int32_t,
 
 /* Set the callback for file data.
  *
- *  Function(Tox *tox, int32_t friendnumber, uint8_t filenumber, uint8_t *data, uint16_t length, void *userdata)
+ *  Function(Tox *tox, uint32_t friendnumber, uint8_t filenumber, uint8_t *data, uint16_t length, void *userdata)
  *
  */
-void callback_file_data(Messenger *m, void (*function)(Messenger *m, int32_t, uint8_t, const uint8_t *, uint16_t length,
+void callback_file_data(Messenger *m, void (*function)(Messenger *m, uint32_t, uint8_t, const uint8_t *,
+                        uint16_t length,
                         void *), void *userdata)
 {
     m->file_filedata = function;
@@ -1397,7 +1399,7 @@ static int handle_filecontrol(const Messenger *m, int32_t friendnumber, uint8_t
  *
  *  Function(Messenger *m, int friendnumber, uint8_t *data, uint16_t length, void *userdata)
  */
-void m_callback_msi_packet(Messenger *m, void (*function)(Messenger *m, int32_t, const uint8_t *, uint16_t, void *),
+void m_callback_msi_packet(Messenger *m, void (*function)(Messenger *m, uint32_t, const uint8_t *, uint16_t, void *),
                            void *userdata)
 {
     m->msi_packet = function;
@@ -1430,7 +1432,7 @@ static int handle_custom_lossy_packet(void *object, int friend_num, const uint8_
 }
 
 int custom_lossy_packet_registerhandler(Messenger *m, int32_t friendnumber, uint8_t byte,
-                                        int (*packet_handler_callback)(Messenger *m, int32_t friendnumber, const uint8_t *data, uint32_t len, void *object),
+                                        int (*packet_handler_callback)(Messenger *m, uint32_t friendnumber, const uint8_t *data, uint32_t len, void *object),
                                         void *object)
 {
     if (friend_not_valid(m, friendnumber))
@@ -1481,7 +1483,7 @@ static int handle_custom_lossless_packet(void *object, int friend_num, const uin
 }
 
 int custom_lossless_packet_registerhandler(Messenger *m, int32_t friendnumber, uint8_t byte,
-        int (*packet_handler_callback)(Messenger *m, int32_t friendnumber, const uint8_t *data, uint32_t len, void *object),
+        int (*packet_handler_callback)(Messenger *m, uint32_t friendnumber, const uint8_t *data, uint32_t len, void *object),
         void *object)
 {
     if (friend_not_valid(m, friendnumber))
@@ -2839,7 +2841,7 @@ uint32_t get_num_online_friends(const Messenger *m)
  * Otherwise, returns the number of elements copied.
  * If the array was too small, the contents
  * of out_list will be truncated to list_size. */
-uint32_t copy_friendlist(Messenger const *m, int32_t *out_list, uint32_t list_size)
+uint32_t copy_friendlist(Messenger const *m, uint32_t *out_list, uint32_t list_size)
 {
     if (!out_list)
         return 0;
diff --git a/toxcore/Messenger.h b/toxcore/Messenger.h
index b1f1c152..db0777cb 100644
--- a/toxcore/Messenger.h
+++ b/toxcore/Messenger.h
@@ -222,12 +222,12 @@ typedef struct {
     AVATAR_RECEIVEDATA *avatar_recv_data;    // We are receiving avatar data from this friend.
 
     struct {
-        int (*function)(Messenger *m, int32_t friendnumber, const uint8_t *data, uint32_t len, void *object);
+        int (*function)(Messenger *m, uint32_t friendnumber, const uint8_t *data, uint32_t len, void *object);
         void *object;
     } lossy_packethandlers[PACKET_ID_LOSSY_RANGE_SIZE];
 
     struct {
-        int (*function)(Messenger *m, int32_t friendnumber, const uint8_t *data, uint32_t len, void *object);
+        int (*function)(Messenger *m, uint32_t friendnumber, const uint8_t *data, uint32_t len, void *object);
         void *object;
     } lossless_packethandlers[PACKET_ID_LOSSLESS_RANGE_SIZE];
 } Friend;
@@ -270,43 +270,43 @@ struct Messenger {
     uint8_t has_added_relays; // If the first connection has occurred in do_messenger
     Node_format loaded_relays[NUM_SAVED_TCP_RELAYS]; // Relays loaded from config
 
-    void (*friend_message)(struct Messenger *m, int32_t, const uint8_t *, uint16_t, void *);
+    void (*friend_message)(struct Messenger *m, uint32_t, const uint8_t *, size_t, void *);
     void *friend_message_userdata;
-    void (*friend_action)(struct Messenger *m, int32_t, const uint8_t *, uint16_t, void *);
+    void (*friend_action)(struct Messenger *m, uint32_t, const uint8_t *, size_t, void *);
     void *friend_action_userdata;
-    void (*friend_namechange)(struct Messenger *m, int32_t, const uint8_t *, uint16_t, void *);
+    void (*friend_namechange)(struct Messenger *m, uint32_t, const uint8_t *, size_t, void *);
     void *friend_namechange_userdata;
-    void (*friend_statusmessagechange)(struct Messenger *m, int32_t, const uint8_t *, uint16_t, void *);
+    void (*friend_statusmessagechange)(struct Messenger *m, uint32_t, const uint8_t *, size_t, void *);
     void *friend_statusmessagechange_userdata;
-    void (*friend_userstatuschange)(struct Messenger *m, int32_t, uint8_t, void *);
+    void (*friend_userstatuschange)(struct Messenger *m, uint32_t, uint8_t, void *);
     void *friend_userstatuschange_userdata;
-    void (*friend_typingchange)(struct Messenger *m, int32_t, uint8_t, void *);
+    void (*friend_typingchange)(struct Messenger *m, uint32_t, uint8_t, void *);
     void *friend_typingchange_userdata;
-    void (*read_receipt)(struct Messenger *m, int32_t, uint32_t, void *);
+    void (*read_receipt)(struct Messenger *m, uint32_t, uint32_t, void *);
     void *read_receipt_userdata;
-    void (*friend_statuschange)(struct Messenger *m, int32_t, uint8_t, void *);
+    void (*friend_statuschange)(struct Messenger *m, uint32_t, uint8_t, void *);
     void *friend_statuschange_userdata;
-    void (*friend_connectionstatuschange)(struct Messenger *m, int32_t, uint8_t, void *);
+    void (*friend_connectionstatuschange)(struct Messenger *m, uint32_t, uint8_t, void *);
     void *friend_connectionstatuschange_userdata;
-    void (*friend_connectionstatuschange_internal)(struct Messenger *m, int32_t, uint8_t, void *);
+    void (*friend_connectionstatuschange_internal)(struct Messenger *m, uint32_t, uint8_t, void *);
     void *friend_connectionstatuschange_internal_userdata;
     void *avatar_info_recv_userdata;
-    void (*avatar_info_recv)(struct Messenger *m, int32_t, uint8_t, uint8_t *, void *);
+    void (*avatar_info_recv)(struct Messenger *m, uint32_t, uint8_t, uint8_t *, void *);
     void *avatar_data_recv_userdata;
-    void (*avatar_data_recv)(struct Messenger *m, int32_t, uint8_t, uint8_t *, uint8_t *, uint32_t, void *);
+    void (*avatar_data_recv)(struct Messenger *m, uint32_t, uint8_t, uint8_t *, uint8_t *, uint32_t, void *);
 
     void *group_chat_object; /* Set by new_groupchats()*/
-    void (*group_invite)(struct Messenger *m, int32_t, const uint8_t *, uint16_t);
-    void (*group_message)(struct Messenger *m, int32_t, const uint8_t *, uint16_t);
+    void (*group_invite)(struct Messenger *m, uint32_t, const uint8_t *, uint16_t);
+    void (*group_message)(struct Messenger *m, uint32_t, const uint8_t *, uint16_t);
 
-    void (*file_sendrequest)(struct Messenger *m, int32_t, uint8_t, uint64_t, const uint8_t *, uint16_t, void *);
+    void (*file_sendrequest)(struct Messenger *m, uint32_t, uint8_t, uint64_t, const uint8_t *, uint16_t, void *);
     void *file_sendrequest_userdata;
-    void (*file_filecontrol)(struct Messenger *m, int32_t, uint8_t, uint8_t, uint8_t, const uint8_t *, uint16_t, void *);
+    void (*file_filecontrol)(struct Messenger *m, uint32_t, uint8_t, uint8_t, uint8_t, const uint8_t *, uint16_t, void *);
     void *file_filecontrol_userdata;
-    void (*file_filedata)(struct Messenger *m, int32_t, uint8_t, const uint8_t *, uint16_t length, void *);
+    void (*file_filedata)(struct Messenger *m, uint32_t, uint8_t, const uint8_t *, uint16_t length, void *);
     void *file_filedata_userdata;
 
-    void (*msi_packet)(struct Messenger *m, int32_t, const uint8_t *, uint16_t, void *);
+    void (*msi_packet)(struct Messenger *m, uint32_t, const uint8_t *, uint16_t, void *);
     void *msi_packet_userdata;
 
     Messenger_Options options;
@@ -624,50 +624,50 @@ uint8_t m_get_istyping(const Messenger *m, int32_t friendnumber);
 void m_set_sends_receipts(Messenger *m, int32_t friendnumber, int yesno);
 
 /* Set the function that will be executed when a friend request is received.
- *  Function format is function(uint8_t * public_key, uint8_t * data, uint16_t length)
+ *  Function format is function(uint8_t * public_key, uint8_t * data, size_t length)
  */
-void m_callback_friendrequest(Messenger *m, void (*function)(Messenger *m, const uint8_t *, const uint8_t *, uint16_t,
+void m_callback_friendrequest(Messenger *m, void (*function)(Messenger *m, const uint8_t *, const uint8_t *, size_t,
                               void *), void *userdata);
 
 /* Set the function that will be executed when a message from a friend is received.
- *  Function format is: function(int32_t friendnumber, uint8_t * message, uint32_t length)
+ *  Function format is: function(uint32_t friendnumber, uint8_t * message, uint32_t length)
  */
-void m_callback_friendmessage(Messenger *m, void (*function)(Messenger *m, int32_t, const uint8_t *, uint16_t, void *),
+void m_callback_friendmessage(Messenger *m, void (*function)(Messenger *m, uint32_t, const uint8_t *, size_t, void *),
                               void *userdata);
 
 /* Set the function that will be executed when an action from a friend is received.
- *  Function format is: function(int32_t friendnumber, uint8_t * action, uint32_t length)
+ *  Function format is: function(uint32_t friendnumber, uint8_t * action, uint32_t length)
  */
-void m_callback_action(Messenger *m, void (*function)(Messenger *m, int32_t, const uint8_t *, uint16_t, void *),
+void m_callback_action(Messenger *m, void (*function)(Messenger *m, uint32_t, const uint8_t *, size_t, void *),
                        void *userdata);
 
 /* Set the callback for name changes.
- *  Function(int32_t friendnumber, uint8_t *newname, uint16_t length)
+ *  Function(uint32_t friendnumber, uint8_t *newname, size_t length)
  *  You are not responsible for freeing newname.
  */
-void m_callback_namechange(Messenger *m, void (*function)(Messenger *m, int32_t, const uint8_t *, uint16_t, void *),
+void m_callback_namechange(Messenger *m, void (*function)(Messenger *m, uint32_t, const uint8_t *, size_t, void *),
                            void *userdata);
 
 /* Set the callback for status message changes.
- *  Function(int32_t friendnumber, uint8_t *newstatus, uint16_t length)
+ *  Function(uint32_t friendnumber, uint8_t *newstatus, size_t length)
  *
  *  You are not responsible for freeing newstatus
  */
-void m_callback_statusmessage(Messenger *m, void (*function)(Messenger *m, int32_t, const uint8_t *, uint16_t, void *),
+void m_callback_statusmessage(Messenger *m, void (*function)(Messenger *m, uint32_t, const uint8_t *, size_t, void *),
                               void *userdata);
 
 /* Set the callback for status type changes.
- *  Function(int32_t friendnumber, USERSTATUS kind)
+ *  Function(uint32_t friendnumber, USERSTATUS kind)
  */
-void m_callback_userstatus(Messenger *m, void (*function)(Messenger *m, int32_t, uint8_t, void *), void *userdata);
+void m_callback_userstatus(Messenger *m, void (*function)(Messenger *m, uint32_t, uint8_t, void *), void *userdata);
 
 /* Set the callback for typing changes.
- *  Function(int32_t friendnumber, uint8_t is_typing)
+ *  Function(uint32_t friendnumber, uint8_t is_typing)
  */
-void m_callback_typingchange(Messenger *m, void(*function)(Messenger *m, int32_t, uint8_t, void *), void *userdata);
+void m_callback_typingchange(Messenger *m, void(*function)(Messenger *m, uint32_t, uint8_t, void *), void *userdata);
 
 /* Set the callback for read receipts.
- *  Function(int32_t friendnumber, uint32_t receipt)
+ *  Function(uint32_t friendnumber, uint32_t receipt)
  *
  *  If you are keeping a record of returns from m_sendmessage,
  *  receipt might be one of those values, meaning the message
@@ -675,10 +675,10 @@ void m_callback_typingchange(Messenger *m, void(*function)(Messenger *m, int32_t
  *  Since core doesn't track ids for you, receipt may not correspond to any message.
  *  In that case, you should discard it.
  */
-void m_callback_read_receipt(Messenger *m, void (*function)(Messenger *m, int32_t, uint32_t, void *), void *userdata);
+void m_callback_read_receipt(Messenger *m, void (*function)(Messenger *m, uint32_t, uint32_t, void *), void *userdata);
 
 /* Set the callback for connection status changes.
- *  function(int32_t friendnumber, uint8_t status)
+ *  function(uint32_t friendnumber, uint8_t status)
  *
  *  Status:
  *    0 -- friend went offline after being previously online.
@@ -688,10 +688,10 @@ void m_callback_read_receipt(Messenger *m, void (*function)(Messenger *m, int32_
  *  being previously online" part.
  *  It's assumed that when adding friends, their connection status is offline.
  */
-void m_callback_connectionstatus(Messenger *m, void (*function)(Messenger *m, int32_t, uint8_t, void *),
+void m_callback_connectionstatus(Messenger *m, void (*function)(Messenger *m, uint32_t, uint8_t, void *),
                                  void *userdata);
 /* Same as previous but for internal A/V core usage only */
-void m_callback_connectionstatus_internal_av(Messenger *m, void (*function)(Messenger *m, int32_t, uint8_t, void *),
+void m_callback_connectionstatus_internal_av(Messenger *m, void (*function)(Messenger *m, uint32_t, uint8_t, void *),
         void *userdata);
 
 
@@ -701,14 +701,14 @@ void m_callback_connectionstatus_internal_av(Messenger *m, void (*function)(Mess
  * information requests.
  *
  * Function format is:
- *  function(Tox *tox, int32_t friendnumber, uint8_t format, uint8_t *hash, void *userdata)
+ *  function(Tox *tox, uint32_t friendnumber, uint8_t format, uint8_t *hash, void *userdata)
  *
  * where 'format' is the avatar image format (see AVATAR_FORMAT) and 'hash' is the hash of
  * the avatar data for caching purposes and it is exactly AVATAR_HASH_LENGTH long. If the
  * image format is NONE, the hash is zeroed.
  *
  */
-void m_callback_avatar_info(Messenger *m, void (*function)(Messenger *m, int32_t, uint8_t, uint8_t *, void *),
+void m_callback_avatar_info(Messenger *m, void (*function)(Messenger *m, uint32_t, uint8_t, uint8_t *, void *),
                             void *userdata);
 
 
@@ -717,7 +717,7 @@ void m_callback_avatar_info(Messenger *m, void (*function)(Messenger *m, int32_t
  * friend. This only happens in reply of a avatar data request (see tox_request_avatar_data);
  *
  * Function format is:
- *  function(Tox *tox, int32_t friendnumber, uint8_t format, uint8_t *hash, uint8_t *data, uint32_t datalen, void *userdata)
+ *  function(Tox *tox, uint32_t friendnumber, uint8_t format, uint8_t *hash, uint8_t *data, uint32_t datalen, void *userdata)
  *
  * where 'format' is the avatar image format (see AVATAR_FORMAT); 'hash' is the
  * locally-calculated cryptographic hash of the avatar data and it is exactly
@@ -732,7 +732,7 @@ void m_callback_avatar_info(Messenger *m, void (*function)(Messenger *m, int32_t
  * potentially malicious. The library only ensures that the data which arrived is the same the
  * other user sent, and does not interpret or validate any image data.
  */
-void m_callback_avatar_data(Messenger *m, void (*function)(Messenger *m, int32_t, uint8_t, uint8_t *, uint8_t *,
+void m_callback_avatar_data(Messenger *m, void (*function)(Messenger *m, uint32_t, uint8_t, uint8_t *, uint8_t *,
                             uint32_t, void *), void *userdata);
 
 
@@ -741,9 +741,9 @@ void m_callback_avatar_data(Messenger *m, void (*function)(Messenger *m, int32_t
 
 /* Set the callback for group invites.
  *
- *  Function(Messenger *m, int32_t friendnumber, uint8_t *data, uint16_t length)
+ *  Function(Messenger *m, uint32_t friendnumber, uint8_t *data, uint16_t length)
  */
-void m_callback_group_invite(Messenger *m, void (*function)(Messenger *m, int32_t, const uint8_t *, uint16_t));
+void m_callback_group_invite(Messenger *m, void (*function)(Messenger *m, uint32_t, const uint8_t *, uint16_t));
 
 /* Send a group invite packet.
  *
@@ -757,25 +757,27 @@ int send_group_invite_packet(const Messenger *m, int32_t friendnumber, const uin
 
 /* Set the callback for file send requests.
  *
- *  Function(Tox *tox, int32_t friendnumber, uint8_t filenumber, uint64_t filesize, uint8_t *filename, uint16_t filename_length, void *userdata)
+ *  Function(Tox *tox, uint32_t friendnumber, uint8_t filenumber, uint64_t filesize, uint8_t *filename, uint16_t filename_length, void *userdata)
  */
-void callback_file_sendrequest(Messenger *m, void (*function)(Messenger *m, int32_t, uint8_t, uint64_t, const uint8_t *,
+void callback_file_sendrequest(Messenger *m, void (*function)(Messenger *m, uint32_t, uint8_t, uint64_t,
+                               const uint8_t *,
                                uint16_t, void *), void *userdata);
 
 /* Set the callback for file control requests.
  *
- *  Function(Tox *tox, int32_t friendnumber, uint8_t send_receive, uint8_t filenumber, uint8_t control_type, uint8_t *data, uint16_t length, void *userdata)
+ *  Function(Tox *tox, uint32_t friendnumber, uint8_t send_receive, uint8_t filenumber, uint8_t control_type, uint8_t *data, uint16_t length, void *userdata)
  *
  */
-void callback_file_control(Messenger *m, void (*function)(Messenger *m, int32_t, uint8_t, uint8_t, uint8_t,
+void callback_file_control(Messenger *m, void (*function)(Messenger *m, uint32_t, uint8_t, uint8_t, uint8_t,
                            const uint8_t *, uint16_t, void *), void *userdata);
 
 /* Set the callback for file data.
  *
- *  Function(Tox *tox, int32_t friendnumber, uint8_t filenumber, uint8_t *data, uint16_t length, void *userdata)
+ *  Function(Tox *tox, uint32_t friendnumber, uint8_t filenumber, uint8_t *data, uint16_t length, void *userdata)
  *
  */
-void callback_file_data(Messenger *m, void (*function)(Messenger *m, int32_t, uint8_t, const uint8_t *, uint16_t length,
+void callback_file_data(Messenger *m, void (*function)(Messenger *m, uint32_t, uint8_t, const uint8_t *,
+                        uint16_t length,
                         void *), void *userdata);
 
 /* Send a file send request.
@@ -823,9 +825,9 @@ uint64_t file_dataremaining(const Messenger *m, int32_t friendnumber, uint8_t fi
 
 /* Set the callback for msi packets.
  *
- *  Function(Messenger *m, int32_t friendnumber, uint8_t *data, uint16_t length, void *userdata)
+ *  Function(Messenger *m, uint32_t friendnumber, uint8_t *data, uint16_t length, void *userdata)
  */
-void m_callback_msi_packet(Messenger *m, void (*function)(Messenger *m, int32_t, const uint8_t *, uint16_t, void *),
+void m_callback_msi_packet(Messenger *m, void (*function)(Messenger *m, uint32_t, const uint8_t *, uint16_t, void *),
                            void *userdata);
 
 /* Send an msi packet.
@@ -843,7 +845,7 @@ int m_msi_packet(const Messenger *m, int32_t friendnumber, const uint8_t *data,
  * return 0 on success.
  */
 int custom_lossy_packet_registerhandler(Messenger *m, int32_t friendnumber, uint8_t byte,
-                                        int (*packet_handler_callback)(Messenger *m, int32_t friendnumber, const uint8_t *data, uint32_t len, void *object),
+                                        int (*packet_handler_callback)(Messenger *m, uint32_t friendnumber, const uint8_t *data, uint32_t len, void *object),
                                         void *object);
 
 /* High level function to send custom lossy packets.
@@ -862,7 +864,7 @@ int send_custom_lossy_packet(const Messenger *m, int32_t friendnumber, const uin
  * return 0 on success.
  */
 int custom_lossless_packet_registerhandler(Messenger *m, int32_t friendnumber, uint8_t byte,
-        int (*packet_handler_callback)(Messenger *m, int32_t friendnumber, const uint8_t *data, uint32_t len, void *object),
+        int (*packet_handler_callback)(Messenger *m, uint32_t friendnumber, const uint8_t *data, uint32_t len, void *object),
         void *object);
 
 /* High level function to send custom lossless packets.
@@ -918,6 +920,6 @@ uint32_t get_num_online_friends(const Messenger *m);
  * Otherwise, returns the number of elements copied.
  * If the array was too small, the contents
  * of out_list will be truncated to list_size. */
-uint32_t copy_friendlist(const Messenger *m, int32_t *out_list, uint32_t list_size);
+uint32_t copy_friendlist(const Messenger *m, uint32_t *out_list, uint32_t list_size);
 
 #endif
diff --git a/toxcore/friend_requests.c b/toxcore/friend_requests.c
index e4a10008..dae1694a 100644
--- a/toxcore/friend_requests.c
+++ b/toxcore/friend_requests.c
@@ -42,7 +42,7 @@ uint32_t get_nospam(const Friend_Requests *fr)
 
 
 /* Set the function that will be executed when a friend request is received. */
-void callback_friendrequest(Friend_Requests *fr, void (*function)(void *, const uint8_t *, const uint8_t *, uint16_t,
+void callback_friendrequest(Friend_Requests *fr, void (*function)(void *, const uint8_t *, const uint8_t *, size_t,
                             void *), void *object, void *userdata)
 {
     fr->handle_friendrequest = function;
diff --git a/toxcore/friend_requests.h b/toxcore/friend_requests.h
index 86069f3b..ae21f7dc 100644
--- a/toxcore/friend_requests.h
+++ b/toxcore/friend_requests.h
@@ -30,7 +30,7 @@
 
 typedef struct {
     uint32_t nospam;
-    void (*handle_friendrequest)(void *, const uint8_t *, const uint8_t *, uint16_t, void *);
+    void (*handle_friendrequest)(void *, const uint8_t *, const uint8_t *, size_t, void *);
     uint8_t handle_friendrequest_isset;
     void *handle_friendrequest_object;
     void *handle_friendrequest_userdata;
@@ -59,9 +59,9 @@ uint32_t get_nospam(const Friend_Requests *fr);
 int remove_request_received(Friend_Requests *fr, const uint8_t *real_pk);
 
 /* Set the function that will be executed when a friend request for us is received.
- *  Function format is function(uint8_t * public_key, uint8_t * data, uint16_t length, void * userdata)
+ *  Function format is function(uint8_t * public_key, uint8_t * data, size_t length, void * userdata)
  */
-void callback_friendrequest(Friend_Requests *fr, void (*function)(void *, const uint8_t *, const uint8_t *, uint16_t,
+void callback_friendrequest(Friend_Requests *fr, void (*function)(void *, const uint8_t *, const uint8_t *, size_t,
                             void *), void *object, void *userdata);
 
 /* Set the function used to check if a friend request should be displayed to the user or not.
diff --git a/toxcore/group.c b/toxcore/group.c
index 786a9cdd..c688ccff 100644
--- a/toxcore/group.c
+++ b/toxcore/group.c
@@ -1236,7 +1236,7 @@ int group_title_get(const Group_Chats *g_c, int groupnumber, uint8_t *title, uin
     return max_length;
 }
 
-static void handle_friend_invite_packet(Messenger *m, int32_t friendnumber, const uint8_t *data, uint16_t length)
+static void handle_friend_invite_packet(Messenger *m, uint32_t friendnumber, const uint8_t *data, uint16_t length)
 {
     Group_Chats *g_c = m->group_chat_object;