diff --git a/auto_tests/TCP_test.c b/auto_tests/TCP_test.c
index 5344c675..cb176184 100644
--- a/auto_tests/TCP_test.c
+++ b/auto_tests/TCP_test.c
@@ -582,7 +582,7 @@ static void test_client(void)
     do_tcp_connection(logger, mono_time, conn2, nullptr);
     c_sleep(50);
 
-    uint8_t data[5] = {1, 2, 3, 4, 5};
+    const uint8_t data[5] = {1, 2, 3, 4, 5};
     memcpy(oob_pubkey, f2_public_key, CRYPTO_PUBLIC_KEY_SIZE);
     send_oob_packet(logger, conn2, f_public_key, data, 5);
     send_routing_request(logger, conn, f2_public_key);
diff --git a/auto_tests/auto_test_support.c b/auto_tests/auto_test_support.c
index fcae32ba..6c3a4cfc 100644
--- a/auto_tests/auto_test_support.c
+++ b/auto_tests/auto_test_support.c
@@ -335,7 +335,7 @@ static void initialise_friend_graph(Graph_Type graph, uint32_t num_toxes, AutoTo
     }
 }
 
-static void bootstrap_autotoxes(struct Tox_Options *options, uint32_t tox_count, const Run_Auto_Options *autotest_opts,
+static void bootstrap_autotoxes(const Tox_Options *options, uint32_t tox_count, const Run_Auto_Options *autotest_opts,
                                 AutoTox *autotoxes)
 {
     const bool udp_enabled = options != nullptr ? tox_options_get_udp_enabled(options) : true;
@@ -363,7 +363,9 @@ static void bootstrap_autotoxes(struct Tox_Options *options, uint32_t tox_count,
     }
 }
 
-void run_auto_test(struct Tox_Options *options, uint32_t tox_count, void test(AutoTox *autotoxes),
+typedef void autotox_test_cb(AutoTox *autotoxes);
+
+void run_auto_test(struct Tox_Options *options, uint32_t tox_count, autotox_test_cb *test,
                    uint32_t state_size, Run_Auto_Options *autotest_opts)
 {
     printf("initialising %u toxes\n", tox_count);
diff --git a/auto_tests/conference_av_test.c b/auto_tests/conference_av_test.c
index 6b8bf5f3..e8c976ae 100644
--- a/auto_tests/conference_av_test.c
+++ b/auto_tests/conference_av_test.c
@@ -108,7 +108,7 @@ static void handle_conference_connected(
 }
 
 static bool toxes_are_disconnected_from_group(uint32_t tox_count, AutoTox *autotoxes,
-        bool *disconnected)
+        const bool *disconnected)
 {
     uint32_t num_disconnected = 0;
 
@@ -177,7 +177,7 @@ static bool all_connected_to_group(uint32_t tox_count, AutoTox *autotoxes)
  * returns a random index at which a list of booleans is false
  * (some such index is required to exist)
  */
-static uint32_t random_false_index(const Random *rng, bool *list, const uint32_t length)
+static uint32_t random_false_index(const Random *rng, const bool *list, const uint32_t length)
 {
     uint32_t index;
 
@@ -197,7 +197,7 @@ static bool all_got_audio(AutoTox *autotoxes, const bool *disabled)
     }
 
     for (uint32_t i = 0; i < NUM_AV_GROUP_TOX; ++i) {
-        State *state = (State *)autotoxes[i].state;
+        const State *state = (const State *)autotoxes[i].state;
 
         if (disabled[i] ^ (state->received_audio_num
                            != NUM_AV_GROUP_TOX - num_disabled - 1)) {
diff --git a/auto_tests/conference_invite_merge_test.c b/auto_tests/conference_invite_merge_test.c
index 4c980905..c9b6a73a 100644
--- a/auto_tests/conference_invite_merge_test.c
+++ b/auto_tests/conference_invite_merge_test.c
@@ -40,7 +40,7 @@ static void handle_conference_connected(
     state->connected = true;
 }
 
-static void wait_connected(AutoTox *autotoxes, AutoTox *autotox, uint32_t friendnumber)
+static void wait_connected(AutoTox *autotoxes, const AutoTox *autotox, uint32_t friendnumber)
 {
     do {
         iterate_all_wait(autotoxes, NUM_INVITE_MERGE_TOX, ITERATION_INTERVAL);
diff --git a/auto_tests/conference_simple_test.c b/auto_tests/conference_simple_test.c
index 189ab35c..6b9290ea 100644
--- a/auto_tests/conference_simple_test.c
+++ b/auto_tests/conference_simple_test.c
@@ -116,7 +116,7 @@ static void handle_conference_connected(Tox *tox, const Tox_Event_Conference_Con
 }
 
 static void iterate_one(
-    Tox *tox, State *state, Tox_Dispatch *dispatch)
+    Tox *tox, State *state, const Tox_Dispatch *dispatch)
 {
     Tox_Err_Events_Iterate err;
     Tox_Events *events = tox_events_iterate(tox, true, &err);
@@ -129,7 +129,7 @@ static void iterate3_wait(
     Tox *tox1, State *state1,
     Tox *tox2, State *state2,
     Tox *tox3, State *state3,
-    Tox_Dispatch *dispatch, int interval)
+    const Tox_Dispatch *dispatch, int interval)
 {
     iterate_one(tox1, state1, dispatch);
     iterate_one(tox2, state2, dispatch);
diff --git a/auto_tests/conference_test.c b/auto_tests/conference_test.c
index e90b3bf3..a300bfc1 100644
--- a/auto_tests/conference_test.c
+++ b/auto_tests/conference_test.c
@@ -97,7 +97,7 @@ static void handle_conference_message(
 }
 
 static bool toxes_are_disconnected_from_group(uint32_t tox_count, AutoTox *autotoxes,
-        bool *disconnected)
+        const bool *disconnected)
 {
     uint32_t num_disconnected = 0;
 
@@ -179,7 +179,7 @@ static bool names_propagated(uint32_t tox_count, AutoTox *autotoxes)
  * returns a random index at which a list of booleans is false
  * (some such index is required to exist)
  */
-static uint32_t random_false_index(const Random *rng, bool *list, const uint32_t length)
+static uint32_t random_false_index(const Random *rng, const bool *list, const uint32_t length)
 {
     uint32_t index;
 
diff --git a/auto_tests/crypto_test.c b/auto_tests/crypto_test.c
index 1d605892..83f8c525 100644
--- a/auto_tests/crypto_test.c
+++ b/auto_tests/crypto_test.c
@@ -274,7 +274,7 @@ static void test_very_large_data(void)
     const Random *rng = os_random();
     ck_assert(rng != nullptr);
 
-    uint8_t nonce[CRYPTO_NONCE_SIZE] = {0};
+    const uint8_t nonce[CRYPTO_NONCE_SIZE] = {0};
     uint8_t pk[CRYPTO_PUBLIC_KEY_SIZE];
     uint8_t sk[CRYPTO_SECRET_KEY_SIZE];
     crypto_new_keypair(rng, pk, sk);
diff --git a/auto_tests/file_streaming_test.c b/auto_tests/file_streaming_test.c
index fdb3d2cb..3f82dbc3 100644
--- a/auto_tests/file_streaming_test.c
+++ b/auto_tests/file_streaming_test.c
@@ -53,7 +53,7 @@ static void tox_file_receive(Tox *tox, uint32_t friend_number, uint32_t file_num
 
     ck_assert_msg(memcmp(file_id, file_cmp_id, TOX_FILE_ID_LENGTH) == 0, "bad file_id");
 
-    uint8_t empty[TOX_FILE_ID_LENGTH] = {0};
+    const uint8_t empty[TOX_FILE_ID_LENGTH] = {0};
 
     ck_assert_msg(memcmp(empty, file_cmp_id, TOX_FILE_ID_LENGTH) != 0, "empty file_id");
 
@@ -209,7 +209,6 @@ static void file_transfer_test(void)
     file_accepted = file_size = sendf_ok = size_recv = 0;
     file_recv = 0;
     max_sending = UINT64_MAX;
-    uint64_t totalf_size = 100 * 1024 * 1024;
 
     printf("Starting file streaming transfer test.\n");
 
@@ -224,7 +223,7 @@ static void file_transfer_test(void)
     tox_callback_file_chunk_request(tox2, tox_file_chunk_request);
     tox_callback_file_recv_control(tox3, file_print_control);
     tox_callback_file_recv(tox3, tox_file_receive);
-    totalf_size = UINT64_MAX;
+    const uint64_t totalf_size = UINT64_MAX;
     Tox_File_Number fnum = tox_file_send(
         tox2, 0, TOX_FILE_KIND_DATA, totalf_size, nullptr,
         (const uint8_t *)"Gentoo.exe", sizeof("Gentoo.exe"), nullptr);
diff --git a/auto_tests/file_transfer_test.c b/auto_tests/file_transfer_test.c
index c1247738..bee68656 100644
--- a/auto_tests/file_transfer_test.c
+++ b/auto_tests/file_transfer_test.c
@@ -63,7 +63,7 @@ static void tox_file_receive(Tox *tox, const Tox_Event_File_Recv *event, void *u
 
     ck_assert_msg(memcmp(file_id, file_cmp_id, TOX_FILE_ID_LENGTH) == 0, "bad file_id");
 
-    uint8_t empty[TOX_FILE_ID_LENGTH] = {0};
+    const uint8_t empty[TOX_FILE_ID_LENGTH] = {0};
 
     ck_assert_msg(memcmp(empty, file_cmp_id, TOX_FILE_ID_LENGTH) != 0, "empty file_id");
 
@@ -175,7 +175,7 @@ static void write_file(Tox *tox, const Tox_Event_File_Recv_Chunk *event, void *u
     size_recv += length;
 }
 
-static void iterate_and_dispatch(Tox_Dispatch *dispatch, Tox *tox)
+static void iterate_and_dispatch(const Tox_Dispatch *dispatch, Tox *tox)
 {
     Tox_Err_Events_Iterate err;
     Tox_Events *events;
diff --git a/auto_tests/forwarding_test.c b/auto_tests/forwarding_test.c
index 2f3c511a..aae6c30b 100644
--- a/auto_tests/forwarding_test.c
+++ b/auto_tests/forwarding_test.c
@@ -47,8 +47,8 @@ static void test_forwarded_request_cb(void *object, const IP_Port *forwarder,
                                       const uint8_t *sendback, uint16_t sendback_length,
                                       const uint8_t *data, uint16_t length, void *userdata)
 {
-    Test_Data *test_data = (Test_Data *)object;
-    uint8_t *index = (uint8_t *)userdata;
+    const Test_Data *test_data = (const Test_Data *)object;
+    const uint8_t *index = (const uint8_t *)userdata;
 
     if (length != 12 || memcmp("hello:  ", data, 8) != 0) {
         printf("[%u] got unexpected data of length %d\n", *index, length);
@@ -66,7 +66,7 @@ static void test_forwarded_response_cb(void *object,
                                        const uint8_t *data, uint16_t length, void *userdata)
 {
     Test_Data *test_data = (Test_Data *)object;
-    uint8_t *index = (uint8_t *)userdata;
+    const uint8_t *index = (const uint8_t *)userdata;
 
     if (length != 12 || memcmp("reply:  ", data, 8) != 0) {
         printf("[%u] got unexpected data of length %d\n", *index, length);
diff --git a/auto_tests/friend_request_test.c b/auto_tests/friend_request_test.c
index 78d950f8..1e0f675a 100644
--- a/auto_tests/friend_request_test.c
+++ b/auto_tests/friend_request_test.c
@@ -26,7 +26,7 @@ static void accept_friend_request(Tox *tox, const Tox_Event_Friend_Request *even
     tox_friend_add_norequest(tox, public_key, nullptr);
 }
 
-static void iterate2_wait(Tox_Dispatch *dispatch, Tox *tox1, Tox *tox2)
+static void iterate2_wait(const Tox_Dispatch *dispatch, Tox *tox1, Tox *tox2)
 {
     Tox_Err_Events_Iterate err;
     Tox_Events *events;
diff --git a/auto_tests/group_general_test.c b/auto_tests/group_general_test.c
index b707f0ea..7b2e215c 100644
--- a/auto_tests/group_general_test.c
+++ b/auto_tests/group_general_test.c
@@ -43,7 +43,7 @@ typedef struct State {
 
 #define PEER_LIMIT 20
 
-static void print_ip(Tox *tox, uint32_t groupnumber, uint32_t peer_id)
+static void print_ip(const Tox *tox, uint32_t groupnumber, uint32_t peer_id)
 {
     Tox_Err_Group_Peer_Query err;
     size_t length = tox_group_peer_get_ip_address_size(tox, groupnumber, peer_id, &err);
@@ -276,7 +276,7 @@ static void group_announce_test(AutoTox *autotoxes)
     Tox *tox0 = autotoxes[0].tox;
     Tox *tox1 = autotoxes[1].tox;
     State *state0 = (State *)autotoxes[0].state;
-    State *state1 = (State *)autotoxes[1].state;
+    const State *state1 = (const State *)autotoxes[1].state;
 
     tox_events_callback_group_peer_join(autotoxes[0].dispatch, group_peer_join_handler);
     tox_events_callback_group_peer_join(autotoxes[1].dispatch, group_peer_join_handler);
diff --git a/auto_tests/group_invite_test.c b/auto_tests/group_invite_test.c
index 11674f74..ebc0c0be 100644
--- a/auto_tests/group_invite_test.c
+++ b/auto_tests/group_invite_test.c
@@ -120,12 +120,12 @@ static void group_invite_test(AutoTox *autotoxes)
     Tox *tox5 = autotoxes[5].tox;
     Tox *tox6 = autotoxes[6].tox;
 
-    State *state0 = (State *)autotoxes[0].state;
-    State *state2 = (State *)autotoxes[2].state;
-    State *state3 = (State *)autotoxes[3].state;
-    State *state4 = (State *)autotoxes[4].state;
-    State *state5 = (State *)autotoxes[5].state;
-    State *state6 = (State *)autotoxes[6].state;
+    const State *state0 = (const State *)autotoxes[0].state;
+    const State *state2 = (const State *)autotoxes[2].state;
+    const State *state3 = (const State *)autotoxes[3].state;
+    const State *state4 = (const State *)autotoxes[4].state;
+    const State *state5 = (const State *)autotoxes[5].state;
+    const State *state6 = (const State *)autotoxes[6].state;
 
     Tox_Err_Group_New new_err;
     uint32_t groupnumber = tox_group_new(tox0, TOX_GROUP_PRIVACY_STATE_PUBLIC, (const uint8_t *)"test", 4,
diff --git a/auto_tests/group_message_test.c b/auto_tests/group_message_test.c
index e37dfdfb..062d5ef8 100644
--- a/auto_tests/group_message_test.c
+++ b/auto_tests/group_message_test.c
@@ -385,7 +385,7 @@ static void group_message_test(AutoTox *autotoxes)
     ck_assert(rng != nullptr);
 
     Tox *tox0 = autotoxes[0].tox;
-    Tox *tox1 = autotoxes[1].tox;
+    const Tox *tox1 = autotoxes[1].tox;
 
     State *state0 = (State *)autotoxes[0].state;
     State *state1 = (State *)autotoxes[1].state;
diff --git a/auto_tests/group_moderation_test.c b/auto_tests/group_moderation_test.c
index e7fae5ce..0c6361c1 100644
--- a/auto_tests/group_moderation_test.c
+++ b/auto_tests/group_moderation_test.c
@@ -53,7 +53,7 @@ typedef struct State {
 static bool all_peers_connected(AutoTox *autotoxes)
 {
     for (size_t i = 0; i < NUM_GROUP_TOXES; ++i) {
-        State *state = (State *)autotoxes[i].state;
+        const State *state = (const State *)autotoxes[i].state;
 
         if (state->num_peers != NUM_GROUP_TOXES - 1) {
             return false;
@@ -146,7 +146,7 @@ static size_t get_state_index_by_nick(const AutoTox *autotoxes, size_t num_peers
     ck_assert(name != nullptr && name_length <= TOX_MAX_NAME_LENGTH);
 
     for (size_t i = 0; i < num_peers; ++i) {
-        State *state = (State *)autotoxes[i].state;
+        const State *state = (const State *)autotoxes[i].state;
 
         if (memcmp(state->self_name, name, name_length) == 0) {
             return i;
@@ -319,7 +319,7 @@ static void check_self_role(AutoTox *autotoxes, uint32_t peer_id, Tox_Group_Role
     Tox_Err_Group_Self_Query sq_err;
 
     for (size_t i = 0; i < NUM_GROUP_TOXES; ++i) {
-        State *state = (State *)autotoxes[i].state;
+        const State *state = (const State *)autotoxes[i].state;
 
         uint32_t self_peer_id = tox_group_self_get_peer_id(autotoxes[i].tox, state->group_number, &sq_err);
         ck_assert(sq_err == TOX_ERR_GROUP_SELF_QUERY_OK);
@@ -517,7 +517,7 @@ static void group_moderation_test(AutoTox *autotoxes)
 
     /* all peers should be user role except founder */
     for (size_t i = 1; i < NUM_GROUP_TOXES; ++i) {
-        State *state = (State *)autotoxes[i].state;
+        const State *state = (const State *)autotoxes[i].state;
         self_role = tox_group_self_get_role(autotoxes[i].tox, state->group_number, &sq_err);
         ck_assert(sq_err == TOX_ERR_GROUP_SELF_QUERY_OK);
         ck_assert(self_role == TOX_GROUP_ROLE_USER);
@@ -615,7 +615,7 @@ static void group_moderation_test(AutoTox *autotoxes)
     /* the moderator about to be kicked changes the topic to trigger the founder to
      * re-sign and redistribute it after the kick.
      */
-    State *state_x = (State *)autotoxes[idx].state;
+    const State *state_x = (const State *)autotoxes[idx].state;
     Tox *tox_x = autotoxes[idx].tox;
     Tox_Err_Group_Topic_Set topic_err;
     tox_group_set_topic(tox_x, state_x->group_number, nullptr, 0, &topic_err);
diff --git a/auto_tests/onion_test.c b/auto_tests/onion_test.c
index dd175d4b..dc78f388 100644
--- a/auto_tests/onion_test.c
+++ b/auto_tests/onion_test.c
@@ -37,7 +37,7 @@ static void do_onion(Mono_Time *mono_time, Onion *onion)
 static int handled_test_1;
 static int handle_test_1(void *object, const IP_Port *source, const uint8_t *packet, uint16_t length, void *userdata)
 {
-    Onion *onion = (Onion *)object;
+    const Onion *onion = (const Onion *)object;
 
     const char req_message[] = "Install Gentoo";
     uint8_t req_packet[1 + sizeof(req_message)];
@@ -99,7 +99,7 @@ static uint8_t test_3_pub_key[CRYPTO_PUBLIC_KEY_SIZE];
 static uint8_t test_3_ping_id[CRYPTO_SHA256_SIZE];
 static int handle_test_3(void *object, const IP_Port *source, const uint8_t *packet, uint16_t length, void *userdata)
 {
-    Onion *onion = (Onion *)object;
+    const Onion *onion = (const Onion *)object;
 
     if (length < ONION_ANNOUNCE_RESPONSE_MIN_SIZE || length > ONION_ANNOUNCE_RESPONSE_MAX_SIZE) {
         return 1;
@@ -135,7 +135,7 @@ static int handle_test_3(void *object, const IP_Port *source, const uint8_t *pac
 static int handle_test_3_old(void *object, const IP_Port *source, const uint8_t *packet, uint16_t length,
                              void *userdata)
 {
-    Onion *onion = (Onion *)object;
+    const Onion *onion = (const Onion *)object;
 
     if (length < ONION_ANNOUNCE_RESPONSE_MIN_SIZE || length > ONION_ANNOUNCE_RESPONSE_MAX_SIZE) {
         return 1;
@@ -171,7 +171,7 @@ static uint8_t nonce[CRYPTO_NONCE_SIZE];
 static int handled_test_4;
 static int handle_test_4(void *object, const IP_Port *source, const uint8_t *packet, uint16_t length, void *userdata)
 {
-    Onion *onion = (Onion *)object;
+    const Onion *onion = (const Onion *)object;
 
     if (length != (1 + CRYPTO_NONCE_SIZE + CRYPTO_PUBLIC_KEY_SIZE + sizeof("Install gentoo") +
                    CRYPTO_MAC_SIZE)) {
@@ -288,7 +288,7 @@ static void test_basic(void)
     networking_registerhandler(onion1->net, NET_PACKET_ANNOUNCE_RESPONSE, &handle_test_3, onion1);
     networking_registerhandler(onion1->net, NET_PACKET_ANNOUNCE_RESPONSE_OLD, &handle_test_3_old, onion1);
     ck_assert_msg((onion1_a != nullptr) && (onion2_a != nullptr), "Onion_Announce failed initializing.");
-    uint8_t zeroes[64] = {0};
+    const uint8_t zeroes[64] = {0};
     random_bytes(rng, sb_data, sizeof(sb_data));
     uint64_t s;
     memcpy(&s, sb_data, sizeof(uint64_t));
diff --git a/other/DHT_bootstrap.c b/other/DHT_bootstrap.c
index 5ae407ed..a99f7010 100644
--- a/other/DHT_bootstrap.c
+++ b/other/DHT_bootstrap.c
@@ -184,7 +184,7 @@ int main(int argc, char *argv[])
 
 #ifdef TCP_RELAY_ENABLED
 #define NUM_PORTS 3
-    uint16_t ports[NUM_PORTS] = {443, 3389, PORT};
+    const uint16_t ports[NUM_PORTS] = {443, 3389, PORT};
     TCP_Server *tcp_s = new_tcp_server(logger, mem, rng, ns, ipv6enabled, NUM_PORTS, ports, dht_get_self_secret_key(dht), onion, forwarding);
 
     if (tcp_s == nullptr) {