diff --git a/src/plugins/irc/irc-bar-item.c b/src/plugins/irc/irc-bar-item.c
index 4e77f96a0..1d4da6511 100644
--- a/src/plugins/irc/irc-bar-item.c
+++ b/src/plugins/irc/irc-bar-item.c
@@ -543,7 +543,6 @@ irc_bar_item_nick_modes (const void *pointer, void *data,
 {
     struct t_irc_server *server;
     char *buf;
-    int length;
 
     /* make C compiler happy */
     (void) pointer;
@@ -559,14 +558,9 @@ irc_bar_item_nick_modes (const void *pointer, void *data,
     if (!server || !server->nick_modes || !server->nick_modes[0])
         return NULL;
 
-    length = 64 + strlen (server->nick_modes) + 1;
-    buf = malloc (length);
-    if (buf)
-    {
-        snprintf (buf, length, "%s%s",
-                  IRC_COLOR_ITEM_NICK_MODES,
-                  server->nick_modes);
-    }
+    weechat_asprintf (&buf,
+                      "%s%s",
+                      IRC_COLOR_ITEM_NICK_MODES, server->nick_modes);
 
     return buf;
 }
diff --git a/src/plugins/irc/irc-channel.c b/src/plugins/irc/irc-channel.c
index f58999e17..e2e0a1d70 100644
--- a/src/plugins/irc/irc-channel.c
+++ b/src/plugins/irc/irc-channel.c
@@ -1482,26 +1482,15 @@ irc_channel_rejoin (struct t_irc_server *server, struct t_irc_channel *channel,
                     int manual_join, int noswitch)
 {
     char *join_string;
-    int length;
 
     if (channel->key)
     {
-        length = strlen (channel->name) + 1 + strlen (channel->key) + 1;
-        join_string = malloc (length);
-        if (join_string)
-        {
-            snprintf (join_string, length, "%s %s",
-                      channel->name,
-                      channel->key);
-            irc_command_join_server (server, join_string,
-                                     manual_join, noswitch);
-            free (join_string);
-        }
-        else
-        {
-            irc_command_join_server (server, channel->name,
-                                     manual_join, noswitch);
-        }
+        weechat_asprintf (&join_string, "%s %s", channel->name, channel->key);
+        irc_command_join_server (server,
+                                 (join_string) ? join_string : channel->name,
+                                 manual_join,
+                                 noswitch);
+        free (join_string);
     }
     else
     {
diff --git a/src/plugins/irc/irc-command.c b/src/plugins/irc/irc-command.c
index 1b90c48e8..5afbedc90 100644
--- a/src/plugins/irc/irc-command.c
+++ b/src/plugins/irc/irc-command.c
@@ -2717,13 +2717,8 @@ IRC_COMMAND_CALLBACK(ignore)
         }
         else
         {
-            length = 1 + strlen (ptr_regex) + 1 + 1;
-            regex2 = malloc (length);
-            if (regex2)
-            {
-                snprintf (regex2, length, "^%s$", ptr_regex);
+            if (weechat_asprintf (&regex2, "^%s$", ptr_regex) >= 0)
                 ptr_regex = regex2;
-            }
         }
 
         ptr_ignore = irc_ignore_search (ptr_regex, server, channel);
@@ -3272,7 +3267,6 @@ IRC_COMMAND_CALLBACK(kick)
 IRC_COMMAND_CALLBACK(kickban)
 {
     char *pos_channel, *pos_nick, *nick_only, *pos_comment, *pos, *mask;
-    int length;
 
     IRC_BUFFER_GET_SERVER_CHANNEL(buffer);
     IRC_COMMAND_CHECK_SERVER("kickban", 1, 1);
@@ -3331,13 +3325,11 @@ IRC_COMMAND_CALLBACK(kickban)
     /* set ban for nick(+host) on channel */
     if (strchr (pos_nick, '@'))
     {
-        length = strlen (pos_nick) + 16 + 1;
-        mask = malloc (length);
-        if (mask)
+        pos = strchr (pos_nick, '!');
+        if (weechat_asprintf (&mask,
+                              "*!%s",
+                              (pos) ? pos + 1 : pos_nick) >= 0)
         {
-            pos = strchr (pos_nick, '!');
-            snprintf (mask, length, "*!%s",
-                      (pos) ? pos + 1 : pos_nick);
             irc_server_sendf (ptr_server,
                               IRC_SERVER_SEND_OUTQ_PRIO_HIGH, NULL,
                               "MODE %s +b %s",
@@ -6187,12 +6179,8 @@ IRC_COMMAND_CALLBACK(server)
         length = strlen (msg_no_quotes);
         if (length > 0)
         {
-            /* allocate length + 2 (CR-LF) + 1 (final '\0') */
-            message = malloc (length + 2 + 1);
-            if (message)
+            if (weechat_asprintf (&message, "%s\r\n", msg_no_quotes) >= 0)
             {
-                strcpy (message, msg_no_quotes);
-                strcat (message, "\r\n");
                 irc_server_msgq_add_buffer (ptr_server, message);
                 irc_server_msgq_flush ();
                 free (message);
diff --git a/src/plugins/irc/irc-completion.c b/src/plugins/irc/irc-completion.c
index 7d5b6542d..14e5e2255 100644
--- a/src/plugins/irc/irc-completion.c
+++ b/src/plugins/irc/irc-completion.c
@@ -414,7 +414,6 @@ irc_completion_channel_nicks_hosts_cb (const void *pointer, void *data,
 {
     struct t_irc_nick *ptr_nick;
     char *buf;
-    int length;
 
     IRC_BUFFER_GET_SERVER_CHANNEL(buffer);
 
@@ -437,13 +436,11 @@ irc_completion_channel_nicks_hosts_cb (const void *pointer, void *data,
                                                  WEECHAT_LIST_POS_SORT);
                     if (ptr_nick->host)
                     {
-                        length = strlen (ptr_nick->name) + 1 +
-                            strlen (ptr_nick->host) + 1;
-                        buf = malloc (length);
-                        if (buf)
+                        if (weechat_asprintf (&buf,
+                                              "%s!%s",
+                                              ptr_nick->name,
+                                              ptr_nick->host) >= 0)
                         {
-                            snprintf (buf, length, "%s!%s",
-                                      ptr_nick->name, ptr_nick->host);
                             weechat_completion_list_add (
                                 completion, buf, 0, WEECHAT_LIST_POS_SORT);
                             free (buf);
@@ -558,7 +555,6 @@ irc_completion_channel_topic_cb (const void *pointer, void *data,
                                  struct t_gui_completion *completion)
 {
     char *topic;
-    int length;
 
     IRC_BUFFER_GET_SERVER_CHANNEL(buffer);
 
@@ -580,16 +576,15 @@ irc_completion_channel_topic_cb (const void *pointer, void *data,
              * instead of
              *   /topic #test is a test channel
              */
-            length = strlen (ptr_channel->name) + strlen (ptr_channel->topic) + 16 + 1;
-            topic = malloc (length);
-            if (topic)
-            {
-                snprintf (topic, length, "%s %s",
-                          ptr_channel->name, ptr_channel->topic);
-            }
+            weechat_asprintf (&topic,
+                              "%s %s",
+                              ptr_channel->name,
+                              ptr_channel->topic);
         }
         else
+        {
             topic = strdup (ptr_channel->topic);
+        }
 
         weechat_completion_list_add (completion,
                                      (topic) ? topic : ptr_channel->topic,
diff --git a/src/plugins/irc/irc-ctcp.c b/src/plugins/irc/irc-ctcp.c
index 0d1b54eb4..3296de3c8 100644
--- a/src/plugins/irc/irc-ctcp.c
+++ b/src/plugins/irc/irc-ctcp.c
@@ -424,7 +424,7 @@ irc_ctcp_reply_to_nick (struct t_irc_protocol_ctxt *ctxt,
                         const char *arguments)
 {
     struct t_arraylist *list_messages;
-    int i, list_size, length;
+    int i, list_size;
     char *dup_ctcp, *dup_ctcp_upper, *dup_args, *message;
     const char *ptr_message;
 
@@ -479,12 +479,11 @@ irc_ctcp_reply_to_nick (struct t_irc_protocol_ctxt *ctxt,
             if (!ptr_message)
                 break;
             /* build arguments: '\001' + CTCP + ' ' + message + '\001' */
-            length = 1 + strlen (dup_ctcp_upper) + 1 + strlen (ptr_message) + 1 + 1;
-            message = malloc (length);
-            if (message)
+            if (weechat_asprintf (&message,
+                                  "\001%s %s\001",
+                                  dup_ctcp_upper,
+                                  ptr_message) >= 0)
             {
-                snprintf (message, length,
-                          "\001%s %s\001", dup_ctcp_upper, ptr_message);
                 irc_ctcp_display_reply_to_nick (ctxt, ctxt->nick, message);
                 free (message);
             }
diff --git a/src/plugins/irc/irc-info.c b/src/plugins/irc/irc-info.c
index b15faeaa1..14b57397b 100644
--- a/src/plugins/irc/irc-info.c
+++ b/src/plugins/irc/irc-info.c
@@ -53,13 +53,7 @@ irc_info_create_string_with_pointer (char **string, void *pointer)
         *string = NULL;
     }
     if (pointer)
-    {
-        *string = malloc (64);
-        if (*string)
-        {
-            snprintf (*string, 64, "0x%lx", (unsigned long)pointer);
-        }
-    }
+        weechat_asprintf (string, "0x%lx", (unsigned long)pointer);
 }
 
 /*
diff --git a/src/plugins/irc/irc-message.c b/src/plugins/irc/irc-message.c
index 21ccf1492..0d931fafd 100644
--- a/src/plugins/irc/irc-message.c
+++ b/src/plugins/irc/irc-message.c
@@ -943,23 +943,22 @@ irc_message_split_add (struct t_irc_message_split_context *context,
 
     if (message)
     {
-        length = ((tags) ? strlen (tags) : 0) + strlen (message) + 1;
-        buf = malloc (length);
-        if (buf)
+        snprintf (key, sizeof (key), "msg%d", context->number);
+        if (weechat_asprintf (&buf,
+                              "%s%s",
+                              (tags) ? tags : "",
+                              message) >= 0)
         {
-            snprintf (key, sizeof (key), "msg%d", context->number);
-            snprintf (buf, length, "%s%s",
-                      (tags) ? tags : "",
-                      message);
+            length = strlen (buf);
             weechat_hashtable_set (context->hashtable, key, buf);
             if (weechat_irc_plugin->debug >= 2)
             {
                 weechat_printf (NULL,
                                 "irc_message_split_add >> %s='%s' (%d bytes)",
-                                key, buf, length - 1);
+                                key, buf, length);
             }
             free (buf);
-            context->total_bytes += length;
+            context->total_bytes += length + 1;
         }
     }
     if (arguments)
diff --git a/src/plugins/irc/irc-mode.c b/src/plugins/irc/irc-mode.c
index 9c13ae8e5..a986e1c90 100644
--- a/src/plugins/irc/irc-mode.c
+++ b/src/plugins/irc/irc-mode.c
@@ -155,7 +155,7 @@ irc_mode_channel_update (struct t_irc_server *server,
 {
     char *pos_args, *str_modes, **argv, *pos, *ptr_arg;
     char *new_modes, *new_args, str_mode[2], *str_temp;
-    int argc, current_arg, chanmode_found, length;
+    int argc, current_arg, chanmode_found;
 
     if (!channel->modes)
         channel->modes = strdup ("+");
@@ -295,11 +295,8 @@ irc_mode_channel_update (struct t_irc_server *server,
         }
         if (new_args[0])
         {
-            length = strlen (new_modes) + 1 + strlen (new_args) + 1;
-            str_temp = malloc (length);
-            if (str_temp)
+            if (weechat_asprintf (&str_temp, "%s %s", new_modes, new_args) >= 0)
             {
-                snprintf (str_temp, length, "%s %s", new_modes, new_args);
                 free (channel->modes);
                 channel->modes = str_temp;
             }
diff --git a/src/plugins/irc/irc-notify.c b/src/plugins/irc/irc-notify.c
index 8d49d89e0..dd8072a22 100644
--- a/src/plugins/irc/irc-notify.c
+++ b/src/plugins/irc/irc-notify.c
@@ -274,42 +274,28 @@ irc_notify_build_message_with_nicks (struct t_irc_server *server,
                                      const char *separator,
                                      int *num_nicks)
 {
-    char *message, *message2;
-    int length, total_length, length_separator;
     struct t_irc_notify *ptr_notify;
+    char **message;
 
     *num_nicks = 0;
 
-    length = strlen (irc_message) + 1;
-    total_length = length;
-    length_separator = strlen (separator);
-
-    message = malloc (length);
+    message = weechat_string_dyn_alloc (256);
     if (!message)
         return NULL;
-    snprintf (message, length, "%s", irc_message);
+
+    weechat_string_dyn_concat (message, irc_message, -1);
 
     for (ptr_notify = server->notify_list; ptr_notify;
          ptr_notify = ptr_notify->next_notify)
     {
-        length = strlen (ptr_notify->nick);
-        total_length += length + length_separator;
-        message2 = realloc (message, total_length);
-        if (!message2)
-        {
-            free (message);
-            message = NULL;
-            break;
-        }
-        message = message2;
         if (*num_nicks > 0)
-            strcat (message, separator);
-        strcat (message, ptr_notify->nick);
+            weechat_string_dyn_concat (message, separator, -1);
+        weechat_string_dyn_concat (message, ptr_notify->nick, -1);
 
         (*num_nicks)++;
     }
 
-    return message;
+    return weechat_string_dyn_free (message, 0);
 }
 
 /*
@@ -646,21 +632,15 @@ irc_notify_send_signal (struct t_irc_notify *notify,
                         const char *away_message)
 {
     char signal[128], *data;
-    int length;
 
     snprintf (signal, sizeof (signal), "irc_notify_%s", type);
 
-    length = strlen (notify->server->name) + 1 + strlen (notify->nick) + 1
-        + ((away_message) ? strlen (away_message) : 0) + 1;
-    data = malloc (length);
-    if (data)
-    {
-        snprintf (data, length, "%s,%s%s%s",
-                  notify->server->name,
-                  notify->nick,
-                  (away_message && away_message[0]) ? "," : "",
-                  (away_message && away_message[0]) ? away_message : "");
-    }
+    weechat_asprintf (&data,
+                      "%s,%s%s%s",
+                      notify->server->name,
+                      notify->nick,
+                      (away_message && away_message[0]) ? "," : "",
+                      (away_message && away_message[0]) ? away_message : "");
 
     (void) weechat_hook_signal_send (signal, WEECHAT_HOOK_SIGNAL_STRING, data);
 
diff --git a/src/plugins/irc/irc-protocol.c b/src/plugins/irc/irc-protocol.c
index 4c6bfbc9d..1bb8ceccd 100644
--- a/src/plugins/irc/irc-protocol.c
+++ b/src/plugins/irc/irc-protocol.c
@@ -5998,7 +5998,6 @@ IRC_PROTOCOL_CALLBACK(352)
 {
     char *str_host, *str_hopcount, *str_realname;
     const char *pos;
-    int length;
     struct t_irc_channel *ptr_channel;
     struct t_irc_nick *ptr_nick;
 
@@ -6037,11 +6036,11 @@ IRC_PROTOCOL_CALLBACK(352)
     /* update host in nick */
     if (ptr_nick)
     {
-        length = strlen (ctxt->params[2]) + 1 + strlen (ctxt->params[3]) + 1;
-        str_host = malloc (length);
-        if (str_host)
+        if (weechat_asprintf (&str_host,
+                              "%s@%s",
+                              ctxt->params[2],
+                              ctxt->params[3]) >= 0)
         {
-            snprintf (str_host, length, "%s@%s", ctxt->params[2], ctxt->params[3]);
             irc_nick_set_host (ptr_nick, str_host);
             free (str_host);
         }
@@ -6267,7 +6266,6 @@ IRC_PROTOCOL_CALLBACK(353)
 IRC_PROTOCOL_CALLBACK(354)
 {
     char *str_params, *str_host;
-    int length;
     struct t_irc_channel *ptr_channel;
     struct t_irc_nick *ptr_nick;
 
@@ -6311,11 +6309,11 @@ IRC_PROTOCOL_CALLBACK(354)
     /* update host in nick */
     if (ptr_nick)
     {
-        length = strlen (ctxt->params[2]) + 1 + strlen (ctxt->params[3]) + 1;
-        str_host = malloc (length);
-        if (str_host)
+        if (weechat_asprintf (&str_host,
+                              "%s@%s",
+                              ctxt->params[2],
+                              ctxt->params[3]) >= 0)
         {
-            snprintf (str_host, length, "%s@%s", ctxt->params[2], ctxt->params[3]);
             irc_nick_set_host (ptr_nick, str_host);
             free (str_host);
         }
diff --git a/src/plugins/irc/irc-sasl.c b/src/plugins/irc/irc-sasl.c
index 5832299ca..f52d7a555 100644
--- a/src/plugins/irc/irc-sasl.c
+++ b/src/plugins/irc/irc-sasl.c
@@ -59,31 +59,33 @@ irc_sasl_mechanism_plain (const char *sasl_username, const char *sasl_password)
     if (!sasl_username || !sasl_password)
         return NULL;
 
-    answer_base64 = NULL;
-    length_username = strlen (sasl_username);
-    length = ((length_username + 1) * 2) + strlen (sasl_password) + 1;
-    string = malloc (length);
-    if (string)
+    if (weechat_asprintf (&string,
+                          "%s|%s|%s",
+                          sasl_username,
+                          sasl_username,
+                          sasl_password) < 0)
     {
-        snprintf (string, length, "%s|%s|%s",
-                  sasl_username, sasl_username, sasl_password);
-        string[length_username] = '\0';
-        string[(length_username * 2) + 1] = '\0';
-
-        answer_base64 = malloc (length * 4);
-        if (answer_base64)
-        {
-            if (weechat_string_base_encode ("64", string, length - 1,
-                                            answer_base64) < 0)
-            {
-                free (answer_base64);
-                answer_base64 = NULL;
-            }
-        }
-
-        free (string);
+        return NULL;
     }
 
+    length = strlen (string);
+
+    length_username = strlen (sasl_username);
+    string[length_username] = '\0';
+    string[(length_username * 2) + 1] = '\0';
+
+    answer_base64 = malloc ((length * 4) + 1);
+    if (answer_base64)
+    {
+        if (weechat_string_base_encode ("64", string, length, answer_base64) < 0)
+        {
+            free (answer_base64);
+            answer_base64 = NULL;
+        }
+    }
+
+    free (string);
+
     return answer_base64;
 }
 
@@ -158,11 +160,11 @@ irc_sasl_mechanism_scram (struct t_irc_server *server,
         if (!username2)
             goto memory_error;
         length = 5 + strlen (username2) + 3 + sizeof (nonce_client_base64) - 1;
-        string = malloc (length + 1);
-        if (string)
+        if (weechat_asprintf (&string,
+                              "n,,n=%s,r=%s",
+                              username2,
+                              nonce_client_base64) >= 0)
         {
-            snprintf (string, length + 1, "n,,n=%s,r=%s",
-                      username2, nonce_client_base64);
             free (server->sasl_scram_client_first);
             server->sasl_scram_client_first = strdup (string + 3);
         }
@@ -366,12 +368,13 @@ irc_sasl_mechanism_scram (struct t_irc_server *server,
                 goto base64_encode_error;
             /* final message: auth_no_proof + "," + proof */
             length = strlen (auth_no_proof) + 3 + strlen (client_proof_base64);
-            string = malloc (length + 1);
-            rc = snprintf (string, length + 1, "%s,p=%s",
-                           auth_no_proof,
-                           client_proof_base64);
-            if ((rc < 0) || (rc >= length + 1))
+            if (weechat_asprintf (&string,
+                                  "%s,p=%s",
+                                  auth_no_proof,
+                                  client_proof_base64) < 0)
+            {
                 goto memory_error;
+            }
         }
     }
     goto end;
@@ -526,8 +529,13 @@ irc_sasl_mechanism_ecdsa_nist256p_challenge (struct t_irc_server *server,
         string = malloc (length + 1);
         if (string)
         {
-            snprintf (string, length + 1, "%s|%s", sasl_username, sasl_username);
-            string[length_username] = '\0';
+            if (weechat_asprintf (&string,
+                                  "%s|%s",
+                                  sasl_username,
+                                  sasl_username) >= 0)
+            {
+                string[length_username] = '\0';
+            }
         }
     }
     else
diff --git a/src/plugins/irc/irc-server.c b/src/plugins/irc/irc-server.c
index 0952757cd..bfd172e63 100644
--- a/src/plugins/irc/irc-server.c
+++ b/src/plugins/irc/irc-server.c
@@ -1707,8 +1707,8 @@ struct t_irc_server *
 irc_server_alloc (const char *name)
 {
     struct t_irc_server *new_server;
-    int i, length;
     char *option_name;
+    int i;
 
     /* check if another server exists with this name */
     if (irc_server_search (name))
@@ -1880,17 +1880,13 @@ irc_server_alloc (const char *name)
     }
     for (i = 0; i < IRC_SERVER_NUM_OPTIONS; i++)
     {
-        length = strlen (new_server->name) + 1 +
-            strlen (irc_server_options[i][0]) +
-            512 +  /* inherited option name (irc.server_default.xxx) */
-            1;
-        option_name = malloc (length);
-        if (option_name)
+        if (weechat_asprintf (
+                &option_name,
+                "%s.%s << irc.server_default.%s",
+                new_server->name,
+                irc_server_options[i][0],
+                irc_server_options[i][0]) >= 0)
         {
-            snprintf (option_name, length, "%s.%s << irc.server_default.%s",
-                      new_server->name,
-                      irc_server_options[i][0],
-                      irc_server_options[i][0]);
             new_server->options[i] = irc_config_server_new_option (
                 irc_config_file,
                 irc_config_section_server,
@@ -1940,7 +1936,7 @@ irc_server_alloc_with_url (const char *irc_url)
     char *pos_address, *pos_port, *pos_channel, *pos;
     char *server_address, *server_nicks, *server_autojoin;
     char default_port[16];
-    int ipv6, tls, length;
+    int ipv6, tls;
     struct t_irc_server *ptr_server;
 
     if (!irc_url || !irc_url[0])
@@ -2062,15 +2058,12 @@ irc_server_alloc_with_url (const char *irc_url)
         ptr_server->temp_server = 1;
         if (pos_address && pos_address[0])
         {
-            length = strlen (pos_address) + 1 +
-                ((pos_port) ? strlen (pos_port) : 16) + 1;
-            server_address = malloc (length);
-            if (server_address)
+            if (weechat_asprintf (
+                    &server_address,
+                    "%s/%s",
+                    pos_address,
+                    (pos_port && pos_port[0]) ? pos_port : default_port) >= 0)
             {
-                snprintf (server_address, length,
-                          "%s/%s",
-                          pos_address,
-                          (pos_port && pos_port[0]) ? pos_port : default_port);
                 weechat_config_option_set (
                     ptr_server->options[IRC_SERVER_OPTION_ADDRESSES],
                     server_address,
@@ -2086,13 +2079,11 @@ irc_server_alloc_with_url (const char *irc_url)
                                    1);
         if (pos_nick && pos_nick[0])
         {
-            length = ((strlen (pos_nick) + 2) * 5) + 1;
-            server_nicks = malloc (length);
-            if (server_nicks)
+            if (weechat_asprintf (
+                    &server_nicks,
+                    "%s,%s2,%s3,%s4,%s5",
+                    pos_nick, pos_nick, pos_nick, pos_nick, pos_nick) >= 0)
             {
-                snprintf (server_nicks, length,
-                          "%s,%s2,%s3,%s4,%s5",
-                          pos_nick, pos_nick, pos_nick, pos_nick, pos_nick);
                 weechat_config_option_set (
                     ptr_server->options[IRC_SERVER_OPTION_NICKS],
                     server_nicks,
@@ -2117,14 +2108,7 @@ irc_server_alloc_with_url (const char *irc_url)
             if (irc_channel_is_channel (ptr_server, pos_channel))
                 server_autojoin = strdup (pos_channel);
             else
-            {
-                server_autojoin = malloc (strlen (pos_channel) + 2);
-                if (server_autojoin)
-                {
-                    strcpy (server_autojoin, "#");
-                    strcat (server_autojoin, pos_channel);
-                }
-            }
+                weechat_asprintf (&server_autojoin, "#%s", pos_channel);
             if (server_autojoin)
             {
                 weechat_config_option_set (
@@ -2460,7 +2444,7 @@ irc_server_copy (struct t_irc_server *server, const char *new_name)
     struct t_infolist *infolist;
     char *mask, *pos;
     const char *option_name;
-    int length, index_option;
+    int index_option;
 
     /* check if another server exists with this name */
     if (irc_server_search (new_name))
@@ -2475,11 +2459,8 @@ irc_server_copy (struct t_irc_server *server, const char *new_name)
     new_server->fake_server = server->fake_server;
 
     /* duplicate options */
-    length = 32 + strlen (server->name) + 1;
-    mask = malloc (length);
-    if (!mask)
+    if (weechat_asprintf (&mask, "irc.server.%s.*", server->name) < 0)
         return 0;
-    snprintf (mask, length, "irc.server.%s.*", server->name);
     infolist = weechat_infolist_get ("option", NULL, mask);
     free (mask);
     if (infolist)
@@ -2521,7 +2502,6 @@ irc_server_copy (struct t_irc_server *server, const char *new_name)
 int
 irc_server_rename (struct t_irc_server *server, const char *new_name)
 {
-    int length;
     char *mask, *pos_option, *new_option_name, charset_modifier[1024];
     char *buffer_name;
     const char *option_name;
@@ -2534,11 +2514,8 @@ irc_server_rename (struct t_irc_server *server, const char *new_name)
         return 0;
 
     /* rename options */
-    length = 32 + strlen (server->name) + 1;
-    mask = malloc (length);
-    if (!mask)
+    if (weechat_asprintf (&mask, "irc.server.%s.*", server->name) < 0)
         return 0;
-    snprintf (mask, length, "irc.server.%s.*", server->name);
     infolist = weechat_infolist_get ("option", NULL, mask);
     free (mask);
     if (infolist)
@@ -2556,12 +2533,11 @@ irc_server_rename (struct t_irc_server *server, const char *new_name)
                     if (pos_option)
                     {
                         pos_option++;
-                        length = strlen (new_name) + 1 + strlen (pos_option) + 1;
-                        new_option_name = malloc (length);
-                        if (new_option_name)
+                        if (weechat_asprintf (&new_option_name,
+                                              "%s.%s",
+                                              new_name,
+                                              pos_option) >= 0)
                         {
-                            snprintf (new_option_name, length,
-                                      "%s.%s", new_name, pos_option);
                             weechat_config_option_rename (ptr_option, new_option_name);
                             free (new_option_name);
                         }
@@ -2677,40 +2653,37 @@ irc_server_send_signal (struct t_irc_server *server, const char *signal,
                         const char *command, const char *full_message,
                         const char *tags)
 {
-    int rc, length;
+    int rc;
     char *str_signal, *full_message_tags;
 
     rc = WEECHAT_RC_OK;
 
-    length = strlen (server->name) + 1 + strlen (signal) + 1
-        + strlen (command) + 1;
-    str_signal = malloc (length);
-    if (str_signal)
+    if (weechat_asprintf (&str_signal,
+                          "%s,%s_%s",
+                          server->name, signal, command) < 0)
     {
-        snprintf (str_signal, length,
-                  "%s,%s_%s", server->name, signal, command);
-        if (tags)
-        {
-            length = strlen (tags) + 1 + strlen (full_message) + 1;
-            full_message_tags = malloc (length);
-            if (full_message_tags)
-            {
-                snprintf (full_message_tags, length,
-                          "%s;%s", tags, full_message);
-                rc = weechat_hook_signal_send (str_signal,
-                                               WEECHAT_HOOK_SIGNAL_STRING,
-                                               (void *)full_message_tags);
-                free (full_message_tags);
-            }
-        }
-        else
+        return rc;
+    }
+
+    if (tags)
+    {
+        if (weechat_asprintf (&full_message_tags,
+                              "%s;%s", tags, full_message) >= 0)
         {
             rc = weechat_hook_signal_send (str_signal,
                                            WEECHAT_HOOK_SIGNAL_STRING,
-                                           (void *)full_message);
+                                           (void *)full_message_tags);
+            free (full_message_tags);
         }
-        free (str_signal);
     }
+    else
+    {
+        rc = weechat_hook_signal_send (str_signal,
+                                       WEECHAT_HOOK_SIGNAL_STRING,
+                                       (void *)full_message);
+    }
+
+    free (str_signal);
 
     return rc;
 }
@@ -2803,7 +2776,6 @@ irc_server_set_send_default_tags (const char *tags)
 char *
 irc_server_get_tags_to_send (const char *tags)
 {
-    int length;
     char *buf;
 
     if (!tags && !irc_server_send_default_tags)
@@ -2816,10 +2788,7 @@ irc_server_get_tags_to_send (const char *tags)
         return strdup (tags);
 
     /* concatenate tags and irc_server_send_default_tags */
-    length = strlen (tags) + 1 + strlen (irc_server_send_default_tags) + 1;
-    buf = malloc (length);
-    if (buf)
-        snprintf (buf, length, "%s,%s", tags, irc_server_send_default_tags);
+    weechat_asprintf (&buf, "%s,%s", tags, irc_server_send_default_tags);
     return buf;
 }
 
@@ -3396,19 +3365,15 @@ irc_server_msgq_add_msg (struct t_irc_server *server, const char *msg)
     message->server = server;
     if (server->unterminated_message)
     {
-        message->data = malloc (strlen (server->unterminated_message) +
-                                strlen (msg) + 1);
-        if (!message->data)
+        if (weechat_asprintf (&message->data,
+                              "%s%s",
+                              server->unterminated_message,
+                              msg) < 0)
         {
             weechat_printf (server->buffer,
                             _("%s%s: not enough memory for received message"),
                             weechat_prefix ("error"), IRC_PLUGIN_NAME);
         }
-        else
-        {
-            strcpy (message->data, server->unterminated_message);
-            strcat (message->data, msg);
-        }
         free (server->unterminated_message);
         server->unterminated_message = NULL;
     }
@@ -4753,22 +4718,18 @@ void
 irc_server_set_buffer_title (struct t_irc_server *server)
 {
     char *title;
-    int length;
 
     if (server && server->buffer)
     {
         if (server->is_connected)
         {
-            length = 16 +
-                ((server->current_address) ? strlen (server->current_address) : 16) +
-                16 + ((server->current_ip) ? strlen (server->current_ip) : 16) + 1;
-            title = malloc (length);
-            if (title)
+            if (weechat_asprintf (
+                    &title,
+                    "IRC: %s/%d (%s)",
+                    server->current_address,
+                    server->current_port,
+                    (server->current_ip) ? server->current_ip : "") >= 0)
             {
-                snprintf (title, length, "IRC: %s/%d (%s)",
-                          server->current_address,
-                          server->current_port,
-                          (server->current_ip) ? server->current_ip : "");
                 weechat_buffer_set (server->buffer, "title", title);
                 free (title);
             }
@@ -5878,7 +5839,6 @@ irc_server_execute_command (struct t_irc_server *server)
 {
     char **commands, **ptr_command, *command2, *command3, *slash_command;
     const char *ptr_server_command;
-    int length;
 
     ptr_server_command = IRC_SERVER_OPTION_STRING(server,
                                                   IRC_SERVER_OPTION_COMMAND);
@@ -5904,11 +5864,8 @@ irc_server_execute_command (struct t_irc_server *server)
                 }
                 else
                 {
-                    length = 1 + strlen (command3) + 1;
-                    slash_command = malloc (length);
-                    if (slash_command)
+                    if (weechat_asprintf (&slash_command, "/%s", command3) >= 0)
                     {
-                        snprintf (slash_command, length, "/%s", command3);
                         weechat_command (server->buffer, slash_command);
                         free (slash_command);
                     }