diff --git a/src/chat.c b/src/chat.c
index 8ef4382..9d6e8a0 100644
--- a/src/chat.c
+++ b/src/chat.c
@@ -510,7 +510,7 @@ static void chat_onFileRecv(ToxWindow *self, Tox *m, uint32_t friendnum, uint32_
                     "Incoming file: %s", filename );
 }
 
-static void chat_onGroupInvite(ToxWindow *self, Tox *m, int32_t friendnumber, const char *invite_data,
+static void chat_onGroupInvite(ToxWindow *self, Tox *m, uint32_t friendnumber, const char *invite_data,
                                size_t length)
 {
     if (self->num != friendnumber)
diff --git a/src/friendlist.c b/src/friendlist.c
index 144d171..e9d8ce6 100644
--- a/src/friendlist.c
+++ b/src/friendlist.c
@@ -496,7 +496,7 @@ static void friendlist_onFileRecv(ToxWindow *self, Tox *m, uint32_t num, uint32_
     sound_notify(prompt, notif_error, NT_WNDALERT_1, NULL);
 }
 
-static void friendlist_onGroupInvite(ToxWindow *self, Tox *m, int32_t num, const char *data, size_t length)
+static void friendlist_onGroupInvite(ToxWindow *self, Tox *m, uint32_t num, const char *data, size_t length)
 {
     if (num >= Friends.max_idx)
         return;
diff --git a/src/toxic.h b/src/toxic.h
index 6535151..a4f456b 100644
--- a/src/toxic.h
+++ b/src/toxic.h
@@ -115,7 +115,7 @@ void on_file_recv(Tox *m, uint32_t friendnumber, uint32_t filenumber, uint32_t k
                   const uint8_t *filename, size_t filename_length, void *userdata);
 void on_typing_change(Tox *m, uint32_t friendnumber, bool is_typing, void *userdata);
 void on_read_receipt(Tox *m, uint32_t friendnumber, uint32_t receipt, void *userdata);
-void on_group_invite(Tox *m, int32_t friendnumber, const uint8_t *invite_data, size_t length, void *userdata);
+void on_group_invite(Tox *m, uint32_t friendnumber, const uint8_t *invite_data, size_t length, void *userdata);
 void on_group_message(Tox *m, uint32_t groupnumber, uint32_t peernumber, TOX_MESSAGE_TYPE type,
                       const uint8_t *message, size_t length, void *userdata);
 void on_group_private_message(Tox *m, uint32_t groupnumber, uint32_t peernumber, const uint8_t *message, size_t length, void *userdata);
diff --git a/src/windows.c b/src/windows.c
index 83a3d8e..e91a24f 100644
--- a/src/windows.c
+++ b/src/windows.c
@@ -151,7 +151,7 @@ void on_friendadded(Tox *m, uint32_t friendnumber, bool sort)
     store_data(m, DATA_FILE);
 }
 
-void on_group_invite(Tox *m, int32_t friendnumber, const uint8_t *invite_data, size_t length, void *userdata)
+void on_group_invite(Tox *m, uint32_t friendnumber, const uint8_t *invite_data, size_t length, void *userdata)
 {
     size_t i;
 
diff --git a/src/windows.h b/src/windows.h
index 99e7c35..010f590 100644
--- a/src/windows.h
+++ b/src/windows.h
@@ -128,7 +128,7 @@ struct ToxWindow {
     void(*onTypingChange)(ToxWindow *, Tox *, uint32_t, bool);
     void(*onReadReceipt)(ToxWindow *, Tox *, uint32_t, uint32_t);
 
-    void(*onGroupInvite)(ToxWindow *, Tox *, int32_t, const char *, size_t);
+    void(*onGroupInvite)(ToxWindow *, Tox *, uint32_t, const char *, size_t);
     void(*onGroupMessage)(ToxWindow *, Tox *, uint32_t, uint32_t, TOX_MESSAGE_TYPE, const char *, size_t);
     void(*onGroupPrivateMessage)(ToxWindow *, Tox *, uint32_t, uint32_t, const char *, size_t);
     void(*onGroupPeerlistUpdate)(ToxWindow *, Tox *, uint32_t);