diff --git a/toxav/msi.c b/toxav/msi.c
index a16d6bf1..736f7acb 100644
--- a/toxav/msi.c
+++ b/toxav/msi.c
@@ -381,7 +381,7 @@ static int msg_parse_in(const Logger *log, MSIMessage *dest, const uint8_t *data
 
     assert(dest != nullptr);
 
-    if (length == 0 || data[length - 1]) { /* End byte must have value 0 */
+    if (length == 0 || data[length - 1] != 0) { /* End byte must have value 0 */
         LOGGER_ERROR(log, "Invalid end byte");
         return -1;
     }
diff --git a/toxav/toxav.c b/toxav/toxav.c
index ea389178..19cd7213 100644
--- a/toxav/toxav.c
+++ b/toxav/toxav.c
@@ -492,7 +492,7 @@ static Toxav_Err_Call_Control call_control_handle_resume(const ToxAVCall *call)
 static Toxav_Err_Call_Control call_control_handle_pause(ToxAVCall *call)
 {
     /* Only act if not already paused */
-    if (!call->msi_call->self_capabilities) {
+    if (call->msi_call->self_capabilities == 0) {
         return TOXAV_ERR_CALL_CONTROL_INVALID_TRANSITION;
     }
 
diff --git a/toxcore/Messenger.c b/toxcore/Messenger.c
index 9a40dda7..7ef95567 100644
--- a/toxcore/Messenger.c
+++ b/toxcore/Messenger.c
@@ -627,7 +627,7 @@ int setname(Messenger *m, const uint8_t *name, uint16_t length)
         return 0;
     }
 
-    if (length) {
+    if (length > 0) {
         memcpy(m->name, name, length);
     }
 
@@ -699,7 +699,7 @@ int m_set_statusmessage(Messenger *m, const uint8_t *status, uint16_t length)
         return 0;
     }
 
-    if (length) {
+    if (length > 0) {
         memcpy(m->statusmessage, status, length);
     }
 
@@ -870,7 +870,7 @@ static int set_friend_statusmessage(const Messenger *m, int32_t friendnumber, co
         return -1;
     }
 
-    if (length) {
+    if (length > 0) {
         memcpy(m->friendlist[friendnumber].statusmessage, status, length);
     }
 
@@ -974,8 +974,8 @@ static void check_friend_connectionstatus(Messenger *m, int32_t friendnumber, ui
         return;
     }
 
-    const uint8_t was_online = m->friendlist[friendnumber].status == FRIEND_ONLINE;
-    const uint8_t is_online = status == FRIEND_ONLINE;
+    const bool was_online = m->friendlist[friendnumber].status == FRIEND_ONLINE;
+    const bool is_online = status == FRIEND_ONLINE;
 
     if (is_online != was_online) {
         if (was_online) {
@@ -1077,14 +1077,14 @@ int file_get_id(const Messenger *m, int32_t friendnumber, uint32_t filenumber, u
     }
 
     uint32_t temp_filenum;
-    uint8_t send_receive;
+    bool send_receive;
     uint8_t file_number;
 
     if (filenumber >= (1 << 16)) {
-        send_receive = 1;
+        send_receive = true;
         temp_filenum = (filenumber >> 16) - 1;
     } else {
-        send_receive = 0;
+        send_receive = false;
         temp_filenum = filenumber;
     }
 
@@ -1134,7 +1134,7 @@ static int file_sendrequest(const Messenger *m, int32_t friendnumber, uint8_t fi
     net_pack_u64(packet + 1 + sizeof(file_type), filesize);
     memcpy(packet + 1 + sizeof(file_type) + sizeof(filesize), file_id, FILE_ID_LENGTH);
 
-    if (filename_length) {
+    if (filename_length > 0) {
         memcpy(packet + 1 + sizeof(file_type) + sizeof(filesize) + FILE_ID_LENGTH, filename, filename_length);
     }
 
@@ -1195,7 +1195,7 @@ long int new_filesender(const Messenger *m, int32_t friendnumber, uint32_t file_
 }
 
 non_null(1) nullable(6)
-static int send_file_control_packet(const Messenger *m, int32_t friendnumber, uint8_t send_receive, uint8_t filenumber,
+static int send_file_control_packet(const Messenger *m, int32_t friendnumber, bool send_receive, uint8_t filenumber,
                                     uint8_t control_type, const uint8_t *data, uint16_t data_length)
 {
     assert(data_length == 0 || data != nullptr);
@@ -1206,11 +1206,11 @@ static int send_file_control_packet(const Messenger *m, int32_t friendnumber, ui
 
     VLA(uint8_t, packet, 3 + data_length);
 
-    packet[0] = send_receive;
+    packet[0] = send_receive ? 1 : 0;
     packet[1] = filenumber;
     packet[2] = control_type;
 
-    if (data_length) {
+    if (data_length > 0) {
         memcpy(packet + 3, data, data_length);
     }
 
@@ -1240,14 +1240,14 @@ int file_control(const Messenger *m, int32_t friendnumber, uint32_t filenumber,
     }
 
     uint32_t temp_filenum;
-    uint8_t send_receive;
+    bool send_receive;
     uint8_t file_number;
 
     if (filenumber >= (1 << 16)) {
-        send_receive = 1;
+        send_receive = true;
         temp_filenum = (filenumber >> 16) - 1;
     } else {
-        send_receive = 0;
+        send_receive = false;
         temp_filenum = filenumber;
     }
 
diff --git a/toxcore/group.c b/toxcore/group.c
index 5cdbc31a..130c9847 100644
--- a/toxcore/group.c
+++ b/toxcore/group.c
@@ -298,7 +298,7 @@ static bool add_to_closest(Group_c *g, const uint8_t *real_pk, const uint8_t *te
     }
 
     for (unsigned int i = 0; i < DESIRED_CLOSEST; ++i) {
-        if (g->closest_peers[i].entry == 0) {
+        if (!g->closest_peers[i].entry) {
             index = i;
             break;
         }
@@ -335,15 +335,15 @@ static bool add_to_closest(Group_c *g, const uint8_t *real_pk, const uint8_t *te
 
     uint8_t old_real_pk[CRYPTO_PUBLIC_KEY_SIZE];
     uint8_t old_temp_pk[CRYPTO_PUBLIC_KEY_SIZE];
-    uint8_t old = 0;
+    bool old = false;
 
     if (g->closest_peers[index].entry) {
         memcpy(old_real_pk, g->closest_peers[index].real_pk, CRYPTO_PUBLIC_KEY_SIZE);
         memcpy(old_temp_pk, g->closest_peers[index].temp_pk, CRYPTO_PUBLIC_KEY_SIZE);
-        old = 1;
+        old = true;
     }
 
-    g->closest_peers[index].entry = 1;
+    g->closest_peers[index].entry = true;
     memcpy(g->closest_peers[index].real_pk, real_pk, CRYPTO_PUBLIC_KEY_SIZE);
     memcpy(g->closest_peers[index].temp_pk, temp_pk, CRYPTO_PUBLIC_KEY_SIZE);
 
@@ -351,7 +351,7 @@ static bool add_to_closest(Group_c *g, const uint8_t *real_pk, const uint8_t *te
         add_to_closest(g, old_real_pk, old_temp_pk);
     }
 
-    if (!g->changed) {
+    if (g->changed == GROUPCHAT_CLOSEST_CHANGE_NONE) {
         g->changed = GROUPCHAT_CLOSEST_CHANGE_ADDED;
     }
 
@@ -428,11 +428,11 @@ static void add_closest_connections(Group_Chats *g_c, uint32_t groupnumber, void
 
         int friendcon_id = getfriend_conn_id_pk(g_c->fr_c, g->closest_peers[i].real_pk);
 
-        uint8_t fresh = 0;
+        bool fresh = false;
 
         if (friendcon_id == -1) {
             friendcon_id = new_friend_connection(g_c->fr_c, g->closest_peers[i].real_pk);
-            fresh = 1;
+            fresh = true;
 
             if (friendcon_id == -1) {
                 continue;
@@ -468,7 +468,7 @@ static bool connect_to_closest(Group_Chats *g_c, uint32_t groupnumber, void *use
         return false;
     }
 
-    if (!g->changed) {
+    if (g->changed == GROUPCHAT_CLOSEST_CHANGE_NONE) {
         return true;
     }
 
@@ -718,7 +718,7 @@ static void remove_from_closest(Group_c *g, int peer_index)
     for (uint32_t i = 0; i < DESIRED_CLOSEST; ++i) {
         if (g->closest_peers[i].entry
                 && id_equal(g->closest_peers[i].real_pk, g->group[peer_index].real_pk)) {
-            g->closest_peers[i].entry = 0;
+            g->closest_peers[i].entry = false;
             g->changed = GROUPCHAT_CLOSEST_CHANGE_REMOVED;
             break;
         }
@@ -905,7 +905,7 @@ static bool setnick(Group_Chats *g_c, uint32_t groupnumber, int peer_index, cons
         return true;
     }
 
-    if (nick_len) {
+    if (nick_len != 0) {
         memcpy(g->group[peer_index].nick, nick, nick_len);
     }
 
@@ -1040,7 +1040,7 @@ static int g_handle_any_status(void *object, int friendcon_id, bool status, void
 {
     Group_Chats *g_c = (Group_Chats *)object;
 
-    if (status) {
+    if (status != 0) {
         rejoin_frozen_friend(g_c, friendcon_id);
     }
 
@@ -1052,7 +1052,7 @@ static int g_handle_status(void *object, int friendcon_id, bool status, void *us
 {
     Group_Chats *g_c = (Group_Chats *)object;
 
-    if (status) { /* Went online */
+    if (status != 0) { /* Went online */
         set_conns_status_groups(g_c, friendcon_id, GROUPCHAT_CONNECTION_ONLINE, userdata);
     } else { /* Went offline */
         set_conns_status_groups(g_c, friendcon_id, GROUPCHAT_CONNECTION_CONNECTING, userdata);
@@ -1095,7 +1095,7 @@ static int add_conn_to_groupchat(Group_Chats *g_c, int friendcon_id, Group_c *g,
             return -1;
         }
 
-        if (lock) {
+        if (lock != 0) {
             friend_connection_lock(g_c->fr_c, friendcon_id);
         }
 
@@ -2276,7 +2276,7 @@ static unsigned int send_peers(const Group_Chats *g_c, const Group_c *g, int fri
         p += g->group[i].nick_len;
     }
 
-    if (g->title_len) {
+    if (g->title_len > 0) {
         VLA(uint8_t, title_packet, 1 + g->title_len);
         title_packet[0] = PEER_TITLE_ID;
         memcpy(title_packet + 1, g->title, g->title_len);
@@ -2467,7 +2467,7 @@ static unsigned int send_lossy_all_connections(const Group_Chats *g_c, const Gro
         const uint64_t comp_val = calculate_comp_value(g->real_pk, real_pk);
 
         for (uint8_t j = 0; j < 2; ++j) {
-            if (j ? (comp_val > comp_val_old[j]) : (comp_val < comp_val_old[j])) {
+            if (j > 0 ? (comp_val > comp_val_old[j]) : (comp_val < comp_val_old[j])) {
                 to_send[j] = connected_closest[i];
                 comp_val_old[j] = comp_val;
             }
@@ -2475,7 +2475,7 @@ static unsigned int send_lossy_all_connections(const Group_Chats *g_c, const Gro
     }
 
     for (uint8_t j = 0; j < 2; ++j) {
-        if (j && to_send[1] == to_send[0]) {
+        if (j > 0 && to_send[1] == to_send[0]) {
             break;
         }
 
@@ -2902,7 +2902,7 @@ static int lossy_packet_not_received(const Group_c *g, int peer_index, uint16_t
     }
 
     if ((uint16_t)(message_number - g->group[peer_index].bottom_lossy_number) < MAX_LOSSY_COUNT) {
-        if (g->group[peer_index].recv_lossy[message_number % MAX_LOSSY_COUNT]) {
+        if (g->group[peer_index].recv_lossy[message_number % MAX_LOSSY_COUNT] != 0) {
             return 1;
         }
 
diff --git a/toxcore/group.h b/toxcore/group.h
index 743f95aa..a298cbe1 100644
--- a/toxcore/group.h
+++ b/toxcore/group.h
@@ -83,7 +83,7 @@ typedef struct Groupchat_Connection {
 } Groupchat_Connection;
 
 typedef struct Groupchat_Closest {
-    uint8_t entry;
+    bool entry;
     uint8_t real_pk[CRYPTO_PUBLIC_KEY_SIZE];
     uint8_t temp_pk[CRYPTO_PUBLIC_KEY_SIZE];
 } Groupchat_Closest;
diff --git a/toxcore/onion_client.c b/toxcore/onion_client.c
index 424f633e..6565bfc8 100644
--- a/toxcore/onion_client.c
+++ b/toxcore/onion_client.c
@@ -56,9 +56,9 @@ typedef struct Last_Pinged {
 
 typedef struct Onion_Friend {
     uint8_t status; /* 0 if friend is not valid, 1 if friend is valid.*/
-    uint8_t is_online; /* Set by the onion_set_friend_status function. */
+    bool is_online;
 
-    uint8_t know_dht_public_key; /* 0 if we don't know the dht public key of the other, 1 if we do. */
+    bool know_dht_public_key;
     uint8_t dht_public_key[CRYPTO_PUBLIC_KEY_SIZE];
     uint8_t real_public_key[CRYPTO_PUBLIC_KEY_SIZE];
 
@@ -212,7 +212,7 @@ static int onion_add_path_node(Onion_Client *onion_c, const IP_Port *ip_port, co
  */
 uint16_t onion_backup_nodes(const Onion_Client *onion_c, Node_format *nodes, uint16_t max_num)
 {
-    if (!max_num) {
+    if (max_num == 0) {
         return 0;
     }
 
@@ -1078,7 +1078,7 @@ int send_onion_data(Onion_Client *onion_c, int friend_num, const uint8_t *data,
 
         ++num_nodes;
 
-        if (list_nodes[i].is_stored) {
+        if (list_nodes[i].is_stored != 0) {
             good_nodes[num_good] = i;
             ++num_good;
         }
@@ -1441,7 +1441,7 @@ int onion_set_friend_DHT_pubkey(Onion_Client *onion_c, int friend_num, const uin
     }
 
     onion_c->friends_list[friend_num].last_seen = mono_time_get(onion_c->mono_time);
-    onion_c->friends_list[friend_num].know_dht_public_key = 1;
+    onion_c->friends_list[friend_num].know_dht_public_key = true;
     memcpy(onion_c->friends_list[friend_num].dht_public_key, dht_key, CRYPTO_PUBLIC_KEY_SIZE);
 
     return 0;
@@ -1492,19 +1492,16 @@ int onion_getfriendip(const Onion_Client *onion_c, int friend_num, IP_Port *ip_p
 /** Set if friend is online or not.
  * NOTE: This function is there and should be used so that we don't send useless packets to the friend if he is online.
  *
- * is_online 1 means friend is online.
- * is_online 0 means friend is offline
- *
  * return -1 on failure.
  * return 0 on success.
  */
-int onion_set_friend_online(Onion_Client *onion_c, int friend_num, uint8_t is_online)
+int onion_set_friend_online(Onion_Client *onion_c, int friend_num, bool is_online)
 {
     if ((uint32_t)friend_num >= onion_c->num_friends) {
         return -1;
     }
 
-    if (is_online == 0 && onion_c->friends_list[friend_num].is_online == 1) {
+    if (!is_online && onion_c->friends_list[friend_num].is_online) {
         onion_c->friends_list[friend_num].last_seen = mono_time_get(onion_c->mono_time);
     }
 
@@ -1791,7 +1788,7 @@ static int onion_isconnected(const Onion_Client *onion_c)
         if (!onion_node_timed_out(&onion_c->clients_announce_list[i], onion_c->mono_time)) {
             ++num;
 
-            if (onion_c->clients_announce_list[i].is_stored) {
+            if (onion_c->clients_announce_list[i].is_stored != 0) {
                 ++announced;
             }
         }
diff --git a/toxcore/onion_client.h b/toxcore/onion_client.h
index 050d1058..b5b0f6ae 100644
--- a/toxcore/onion_client.h
+++ b/toxcore/onion_client.h
@@ -10,6 +10,8 @@
 #ifndef C_TOXCORE_TOXCORE_ONION_CLIENT_H
 #define C_TOXCORE_TOXCORE_ONION_CLIENT_H
 
+#include <stdbool.h>
+
 #include "net_crypto.h"
 #include "onion_announce.h"
 #include "ping_array.h"
@@ -99,14 +101,11 @@ int onion_delfriend(Onion_Client *onion_c, int friend_num);
 /** Set if friend is online or not.
  * NOTE: This function is there and should be used so that we don't send useless packets to the friend if he is online.
  *
- * is_online 1 means friend is online.
- * is_online 0 means friend is offline
- *
  * return -1 on failure.
  * return 0 on success.
  */
 non_null()
-int onion_set_friend_online(Onion_Client *onion_c, int friend_num, uint8_t is_online);
+int onion_set_friend_online(Onion_Client *onion_c, int friend_num, bool is_online);
 
 /** Get the ip of friend friendnum and put it in ip_port
  *