diff --git a/.splintrc b/.splintrc
index 76ca479c..67949a4a 100644
--- a/.splintrc
+++ b/.splintrc
@@ -38,7 +38,6 @@
 +charint
 +matchanyintegral
 +voidabstract
--boolops
 -branchstate
 -compdef
 -compdestroy
@@ -46,7 +45,6 @@
 -exportlocal
 -fcnuse
 -fixedformalarray
--formatcode
 -globstate
 -immediatetrans
 -incondefs
@@ -61,7 +59,6 @@
 -nullret
 -nullstate
 -observertrans
--predboolothers
 -retvalother
 -shiftnegative
 -statictrans
diff --git a/src/alloc.c b/src/alloc.c
index 8507224f..9dda87e7 100644
--- a/src/alloc.c
+++ b/src/alloc.c
@@ -39,7 +39,7 @@ INTERNAL /*@only@*/ /*@notnull@*/ void *otrng_xmalloc(size_t size) {
     if (oom_handler != NULL) {
       oom_handler();
     }
-    fprintf(stderr, "fatal: memory exhausted (xmalloc of %zu bytes).\n", size);
+    fprintf(stderr, "fatal: memory exhausted (xmalloc of %lu bytes).\n", size);
     exit(EXIT_FAILURE);
   }
 
@@ -59,7 +59,7 @@ otrng_xrealloc(/*@only@*/ /*@null@*/ void *ptr, size_t size) {
     if (oom_handler != NULL) {
       oom_handler();
     }
-    fprintf(stderr, "fatal: memory exhausted (xrealloc of %zu bytes).\n", size);
+    fprintf(stderr, "fatal: memory exhausted (xrealloc of %lu bytes).\n", size);
     exit(EXIT_FAILURE);
   }
 
diff --git a/src/client.c b/src/client.c
index 78a97503..7df02d20 100644
--- a/src/client.c
+++ b/src/client.c
@@ -585,7 +585,9 @@ otrng_client_build_prekey_messages(uint8_t num_messages,
   for (i = 0; i < num_messages; i++) {
     ecdh_keypair_s ecdh;
     dh_keypair_s dh;
-    otrng_generate_ephemeral_keys(&ecdh, &dh);
+    if (!otrng_generate_ephemeral_keys(&ecdh, &dh)) {
+      return NULL;
+    }
 
     messages[i] = otrng_prekey_message_build(instance_tag, &ecdh, &dh);
     if (!messages[i]) {
diff --git a/src/client_profile.c b/src/client_profile.c
index 3d6b62fb..3af4da96 100644
--- a/src/client_profile.c
+++ b/src/client_profile.c
@@ -188,7 +188,7 @@ tstatic uint32_t client_profile_body_serialize_pre_transitional_signature(
   num_fields++;
 
   /* DSA key */
-  if (client_profile->dsa_key && client_profile->dsa_key_len) {
+  if ((client_profile->dsa_key != NULL) && (client_profile->dsa_key_len != 0)) {
     w += otrng_serialize_uint16(dst + w, OTRNG_CLIENT_PROFILE_FIELD_DSA_KEY);
     w += otrng_serialize_bytes_array(dst + w, client_profile->dsa_key,
                                      client_profile->dsa_key_len);
diff --git a/src/fingerprint.c b/src/fingerprint.c
index 7eb5dc62..938dede3 100644
--- a/src/fingerprint.c
+++ b/src/fingerprint.c
@@ -55,7 +55,7 @@ INTERNAL otrng_result otrng_serialize_fingerprint(otrng_fingerprint fp,
 
   memset(ser, 0, ED448_POINT_BYTES);
 
-  if (!fp) {
+  if (fp == NULL) { // TODO: unsure about this check. This is an array
     return OTRNG_ERROR;
   }
 
diff --git a/src/fragment.c b/src/fragment.c
index c50633cd..4e3bddc5 100644
--- a/src/fragment.c
+++ b/src/fragment.c
@@ -327,8 +327,8 @@ INTERNAL otrng_result otrng_expire_fragments(time_t now,
     fragment_context_s *ctx = current->data;
 
     list_element_s *to_free = NULL;
-    if (ctx &&
-        difftime(now, ctx->last_fragment_received_at) < expiration_time) {
+    if ((ctx != NULL) &&
+        (difftime(now, ctx->last_fragment_received_at) < expiration_time)) {
       *contexts = otrng_list_remove_element(current, *contexts);
       otrng_fragment_context_free(ctx);
       to_free = current;
diff --git a/src/instance_tag.c b/src/instance_tag.c
index 35700441..d54b5923 100644
--- a/src/instance_tag.c
+++ b/src/instance_tag.c
@@ -38,7 +38,7 @@ API otrng_bool otrng_instag_get(otrng_instag_s *otrng_instag,
   OtrlInsTag *tmp_instag;
   OtrlUserState us = otrl_userstate_create();
 
-  if (!us) {
+  if (us == NULL) { // TODO: unsure about this check
     return otrng_false;
   }
 
diff --git a/src/list.c b/src/list.c
index ba6aa73b..55e384e7 100644
--- a/src/list.c
+++ b/src/list.c
@@ -181,7 +181,7 @@ otrng_list_get(const void *wanted, list_element_s *head,
   list_element_s *cursor = head;
 
   while (cursor) {
-    if (fn && fn(cursor->data, wanted)) {
+    if ((fn != NULL) && fn(cursor->data, wanted)) {
       return cursor;
     }
 
diff --git a/src/otrng.c b/src/otrng.c
index e6dc01f5..e912c660 100644
--- a/src/otrng.c
+++ b/src/otrng.c
@@ -335,12 +335,14 @@ tstatic otrng_result message_to_display_without_tag(otrng_response_s *response,
 }
 
 tstatic void set_running_version_from_tag(otrng_s *otr, const string_p msg) {
-  if (allow_version(otr, OTRNG_ALLOW_V4) && strstr(msg, tag_version_v4)) {
+  if (allow_version(otr, OTRNG_ALLOW_V4) &&
+      (strstr(msg, tag_version_v4) != NULL)) {
     otr->running_version = OTRNG_PROTOCOL_VERSION_4;
     return;
   }
 
-  if (allow_version(otr, OTRNG_ALLOW_V3) && strstr(msg, tag_version_v3)) {
+  if (allow_version(otr, OTRNG_ALLOW_V3) &&
+      (strstr(msg, tag_version_v3) != NULL)) {
     otr->running_version = OTRNG_PROTOCOL_VERSION_3;
     return;
   }
@@ -355,9 +357,9 @@ tstatic otrng_bool message_is_query(const string_p msg) {
 
 tstatic void set_running_version_from_query_message(otrng_s *otr,
                                                     const string_p msg) {
-  if (allow_version(otr, OTRNG_ALLOW_V4) && strstr(msg, "4")) {
+  if (allow_version(otr, OTRNG_ALLOW_V4) && (strstr(msg, "4") != NULL)) {
     otr->running_version = OTRNG_PROTOCOL_VERSION_4;
-  } else if (allow_version(otr, OTRNG_ALLOW_V3) && strstr(msg, "3")) {
+  } else if (allow_version(otr, OTRNG_ALLOW_V3) && (strstr(msg, "3") != NULL)) {
     otr->running_version = OTRNG_PROTOCOL_VERSION_3;
   }
 }
@@ -1225,7 +1227,8 @@ tstatic otrng_bool verify_non_interactive_auth_message(
     free(t);
     t = NULL;
 
-    if (initiator.exp_client_profile && initiator.exp_prekey_profile) {
+    if ((initiator.exp_client_profile != NULL) &&
+        (initiator.exp_prekey_profile != NULL)) {
       /* the fallback */
       if (!build_fallback_non_interactive_rsign_tag(
               &t, &t_len, &initiator, &responder,
@@ -2251,7 +2254,8 @@ static otrng_result receive_defragmented_message(otrng_response_s *response,
   response->to_display = NULL;
 
   /* A DH-Commit sets our running version to 3 */
-  if (allow_version(otr, OTRNG_ALLOW_V3) && strstr(msg, "?OTR:AAMC")) {
+  if (allow_version(otr, OTRNG_ALLOW_V3) &&
+      (strstr(msg, "?OTR:AAMC") != NULL)) {
     otr->running_version = OTRNG_PROTOCOL_VERSION_3;
   }
 
diff --git a/src/persistence.c b/src/persistence.c
index f64c1280..41c7247e 100644
--- a/src/persistence.c
+++ b/src/persistence.c
@@ -40,7 +40,7 @@ static char *otrng_client_get_storage_id(const otrng_client_s *client) {
     return NULL;
   }
 
-  if (account_name && protocol_name) {
+  if ((account_name != NULL) && (protocol_name != NULL)) {
     size_t n = strlen(protocol_name) + strlen(account_name) + 2;
     key = otrng_xmalloc(n);
 
@@ -296,7 +296,8 @@ INTERNAL otrng_result
 otrng_client_instance_tag_read_from(otrng_client_s *client, FILE *instagf) {
   gcry_error_t ret;
 
-  if (!client->global_state->user_state_v3) {
+  if (client->global_state->user_state_v3 ==
+      NULL) { // TODO: unsure about this check. It is not a pointer
     return OTRNG_ERROR;
   }
 
diff --git a/src/protocol.c b/src/protocol.c
index fc9b305a..e410990b 100644
--- a/src/protocol.c
+++ b/src/protocol.c
@@ -222,9 +222,11 @@ tstatic otrng_result send_data_message(string_p *to_send, const uint8_t *msg,
   memset(enc_key, 0, ENC_KEY_BYTES);
   memset(mac_key, 0, MAC_KEY_BYTES);
 
-  otrng_key_manager_derive_chain_keys(enc_key, mac_key, otr->keys, NULL,
-                                      otr->client->max_stored_msg_keys, 0, 's',
-                                      warn);
+  if (!otrng_key_manager_derive_chain_keys(enc_key, mac_key, otr->keys, NULL,
+                                           otr->client->max_stored_msg_keys, 0,
+                                           's', warn)) {
+    return OTRNG_ERROR;
+  }
 
   data_msg = generate_data_message(otr, ratchet_id);
   if (!data_msg) {
diff --git a/src/smp_protocol.c b/src/smp_protocol.c
index a2288442..564b413a 100644
--- a/src/smp_protocol.c
+++ b/src/smp_protocol.c
@@ -1196,7 +1196,10 @@ INTERNAL otrng_smp_event otrng_reply_with_smp_message_2(tlv_s **to_send,
 
   *to_send = NULL;
 
-  generate_smp_message_2(&msg_2, smp->message1, smp);
+  if (!generate_smp_message_2(&msg_2, smp->message1, smp)) {
+    return OTRNG_SMP_EVENT_ERROR;
+  }
+
   if (!smp_message_2_serialize(&buffer, &buff_len, &msg_2)) {
     return OTRNG_SMP_EVENT_ERROR;
   }
diff --git a/src/v3.c b/src/v3.c
index 80d93114..2888e3d7 100644
--- a/src/v3.c
+++ b/src/v3.c
@@ -712,7 +712,7 @@ INTERNAL otrng_result otrng_v3_receive_message(char **to_send,
 
   *to_send = otrng_v3_retrieve_injected_message(conn);
 
-  if (to_display && new_msg) {
+  if ((to_display != NULL) && (new_msg != NULL)) {
     *to_display = otrng_xstrdup(new_msg);
   }
 
@@ -777,7 +777,7 @@ INTERNAL otrng_result otrng_v3_smp_start(char **to_send,
                                          size_t secretlen,
                                          otrng_v3_conn_s *conn) {
   char *q = NULL;
-  if (question && q_len > 0) {
+  if ((question != NULL) && q_len > 0) {
     q = otrng_xmalloc(q_len + 1);
     q = memcpy(q, question, q_len);
     q[q_len] = 0;
@@ -822,7 +822,7 @@ tstatic void otrng_v3_store_injected_message(const char *msg,
 
   // TODO: @client This is where we should ADD a new element to the list.
   // We are just ignoring for now.
-  if (conn->injected_message && msg) {
+  if ((conn->injected_message != NULL) && (msg != NULL)) {
     free(conn->injected_message);
   }