diff --git a/ChangeLog.adoc b/ChangeLog.adoc
index 368c153a3..84c3eb0d2 100644
--- a/ChangeLog.adoc
+++ b/ChangeLog.adoc
@@ -35,6 +35,7 @@ Bug fixes::
   * api: fix add of infolist items in hashtable when prefix contains UTF-8 chars in function hashtable_add_from_infolist (issue #1739)
   * irc: fix completion of channel topic with UTF-8 chars (issue #1739)
   * irc: fix parsing of messages 311, 312, 327 (whois) and 314 (whowas) in case of missing parameters
+  * irc: fix parsing of message 223 (m_filter) sent by InspIRCd server (issue #1751)
   * irc: fix parsing of message 338 (whois, host) sent by Rizon server (issue #1737)
   * irc: fix display of message 344 received as whois geo info (issue #1736)
   * irc: fix display of IRC numeric messages with no parameters
diff --git a/src/plugins/irc/irc-protocol.c b/src/plugins/irc/irc-protocol.c
index 699178743..bcf8e3751 100644
--- a/src/plugins/irc/irc-protocol.c
+++ b/src/plugins/irc/irc-protocol.c
@@ -3951,32 +3951,44 @@ IRC_PROTOCOL_CALLBACK(306)
  *
  * Command looks like:
  *   319 mynick nick :some text here
+ *
+ * On InspIRCd server (not a whois reply):
+ *   223 mynick :EXEMPT #help
  */
 
 IRC_PROTOCOL_CALLBACK(whois_nick_msg)
 {
     char *str_params;
 
-    IRC_PROTOCOL_MIN_PARAMS(3);
+    IRC_PROTOCOL_MIN_PARAMS(2);
 
-    str_params = irc_protocol_string_params (params, 2, num_params - 1);
-
-    weechat_printf_date_tags (
-        irc_msgbuffer_get_target_buffer (
-            server, params[1], command, "whois", NULL),
-        date,
-        irc_protocol_tags (command, tags, "irc_numeric", NULL, NULL),
-        "%s%s[%s%s%s] %s%s",
-        weechat_prefix ("network"),
-        IRC_COLOR_CHAT_DELIMITERS,
-        irc_nick_color_for_msg (server, 1, NULL, params[1]),
-        params[1],
-        IRC_COLOR_CHAT_DELIMITERS,
-        IRC_COLOR_RESET,
-        str_params);
-
-    if (str_params)
-        free (str_params);
+    if (num_params >= 3)
+    {
+        str_params = irc_protocol_string_params (params, 2, num_params - 1);
+        weechat_printf_date_tags (
+            irc_msgbuffer_get_target_buffer (
+                server, params[1], command, "whois", NULL),
+            date,
+            irc_protocol_tags (command, tags, "irc_numeric", NULL, NULL),
+            "%s%s[%s%s%s] %s%s",
+            weechat_prefix ("network"),
+            IRC_COLOR_CHAT_DELIMITERS,
+            irc_nick_color_for_msg (server, 1, NULL, params[1]),
+            params[1],
+            IRC_COLOR_CHAT_DELIMITERS,
+            IRC_COLOR_RESET,
+            str_params);
+        if (str_params)
+            free (str_params);
+    }
+    else
+    {
+        /*
+         * not enough parameters: this should not be a whois command so we
+         * display the arguments as-is
+         */
+        IRC_PROTOCOL_RUN_CALLBACK(numeric);
+    }
 
     return WEECHAT_RC_OK;
 }
@@ -3992,26 +4004,35 @@ IRC_PROTOCOL_CALLBACK(whowas_nick_msg)
 {
     char *str_params;
 
-    IRC_PROTOCOL_MIN_PARAMS(3);
+    IRC_PROTOCOL_MIN_PARAMS(2);
 
-    str_params = irc_protocol_string_params (params, 2, num_params - 1);
-
-    weechat_printf_date_tags (
-        irc_msgbuffer_get_target_buffer (
-            server, params[1], command, "whowas", NULL),
-        date,
-        irc_protocol_tags (command, tags, "irc_numeric", NULL, NULL),
-        "%s%s[%s%s%s] %s%s",
-        weechat_prefix ("network"),
-        IRC_COLOR_CHAT_DELIMITERS,
-        irc_nick_color_for_msg (server, 1, NULL, params[1]),
-        params[1],
-        IRC_COLOR_CHAT_DELIMITERS,
-        IRC_COLOR_RESET,
-        str_params);
-
-    if (str_params)
-        free (str_params);
+    if (num_params >= 3)
+    {
+        str_params = irc_protocol_string_params (params, 2, num_params - 1);
+        weechat_printf_date_tags (
+            irc_msgbuffer_get_target_buffer (
+                server, params[1], command, "whowas", NULL),
+            date,
+            irc_protocol_tags (command, tags, "irc_numeric", NULL, NULL),
+            "%s%s[%s%s%s] %s%s",
+            weechat_prefix ("network"),
+            IRC_COLOR_CHAT_DELIMITERS,
+            irc_nick_color_for_msg (server, 1, NULL, params[1]),
+            params[1],
+            IRC_COLOR_CHAT_DELIMITERS,
+            IRC_COLOR_RESET,
+            str_params);
+        if (str_params)
+            free (str_params);
+    }
+    else
+    {
+        /*
+         * not enough parameters: this should not be a whowas command so we
+         * display the arguments as-is
+         */
+        IRC_PROTOCOL_RUN_CALLBACK(numeric);
+    }
 
     return WEECHAT_RC_OK;
 }
diff --git a/tests/unit/plugins/irc/test-irc-protocol.cpp b/tests/unit/plugins/irc/test-irc-protocol.cpp
index a7ee6eb0b..436ad2e54 100644
--- a/tests/unit/plugins/irc/test-irc-protocol.cpp
+++ b/tests/unit/plugins/irc/test-irc-protocol.cpp
@@ -2239,128 +2239,130 @@ TEST(IrcProtocolWithServer, whois_nick_msg)
 
     /* not enough parameters */
     RECV(":server 223");
-    CHECK_ERROR_PARAMS("223", 0, 3);
+    CHECK_ERROR_PARAMS("223", 0, 2);
     RECV(":server 223 alice");
-    CHECK_ERROR_PARAMS("223", 1, 3);
-    RECV(":server 223 alice bob");
-    CHECK_ERROR_PARAMS("223", 2, 3);
+    CHECK_ERROR_PARAMS("223", 1, 2);
     RECV(":server 264");
-    CHECK_ERROR_PARAMS("264", 0, 3);
+    CHECK_ERROR_PARAMS("264", 0, 2);
     RECV(":server 264 alice");
-    CHECK_ERROR_PARAMS("264", 1, 3);
-    RECV(":server 264 alice bob");
-    CHECK_ERROR_PARAMS("264", 2, 3);
+    CHECK_ERROR_PARAMS("264", 1, 2);
     RECV(":server 275");
-    CHECK_ERROR_PARAMS("275", 0, 3);
+    CHECK_ERROR_PARAMS("275", 0, 2);
     RECV(":server 275 alice");
-    CHECK_ERROR_PARAMS("275", 1, 3);
-    RECV(":server 275 alice bob");
-    CHECK_ERROR_PARAMS("275", 2, 3);
+    CHECK_ERROR_PARAMS("275", 1, 2);
     RECV(":server 276");
-    CHECK_ERROR_PARAMS("276", 0, 3);
+    CHECK_ERROR_PARAMS("276", 0, 2);
     RECV(":server 276 alice");
-    CHECK_ERROR_PARAMS("276", 1, 3);
-    RECV(":server 276 alice bob");
-    CHECK_ERROR_PARAMS("276", 2, 3);
+    CHECK_ERROR_PARAMS("276", 1, 2);
     RECV(":server 307");
-    CHECK_ERROR_PARAMS("307", 0, 3);
+    CHECK_ERROR_PARAMS("307", 0, 2);
     RECV(":server 307 alice");
-    CHECK_ERROR_PARAMS("307", 1, 3);
-    RECV(":server 307 alice bob");
-    CHECK_ERROR_PARAMS("307", 2, 3);
+    CHECK_ERROR_PARAMS("307", 1, 2);
     RECV(":server 310");
-    CHECK_ERROR_PARAMS("310", 0, 3);
+    CHECK_ERROR_PARAMS("310", 0, 2);
     RECV(":server 310 alice");
-    CHECK_ERROR_PARAMS("310", 1, 3);
-    RECV(":server 310 alice bob");
-    CHECK_ERROR_PARAMS("310", 2, 3);
+    CHECK_ERROR_PARAMS("310", 1, 2);
     RECV(":server 313");
-    CHECK_ERROR_PARAMS("313", 0, 3);
+    CHECK_ERROR_PARAMS("313", 0, 2);
     RECV(":server 313 alice");
-    CHECK_ERROR_PARAMS("313", 1, 3);
-    RECV(":server 313 alice bob");
-    CHECK_ERROR_PARAMS("313", 2, 3);
+    CHECK_ERROR_PARAMS("313", 1, 2);
     RECV(":server 318");
-    CHECK_ERROR_PARAMS("318", 0, 3);
+    CHECK_ERROR_PARAMS("318", 0, 2);
     RECV(":server 318 alice");
-    CHECK_ERROR_PARAMS("318", 1, 3);
-    RECV(":server 318 alice bob");
-    CHECK_ERROR_PARAMS("318", 2, 3);
+    CHECK_ERROR_PARAMS("318", 1, 2);
     RECV(":server 319");
-    CHECK_ERROR_PARAMS("319", 0, 3);
+    CHECK_ERROR_PARAMS("319", 0, 2);
     RECV(":server 319 alice");
-    CHECK_ERROR_PARAMS("319", 1, 3);
-    RECV(":server 319 alice bob");
-    CHECK_ERROR_PARAMS("319", 2, 3);
+    CHECK_ERROR_PARAMS("319", 1, 2);
     RECV(":server 320");
-    CHECK_ERROR_PARAMS("320", 0, 3);
+    CHECK_ERROR_PARAMS("320", 0, 2);
     RECV(":server 320 alice");
-    CHECK_ERROR_PARAMS("320", 1, 3);
-    RECV(":server 320 alice bob");
-    CHECK_ERROR_PARAMS("320", 2, 3);
+    CHECK_ERROR_PARAMS("320", 1, 2);
     RECV(":server 326");
-    CHECK_ERROR_PARAMS("326", 0, 3);
+    CHECK_ERROR_PARAMS("326", 0, 2);
     RECV(":server 326 alice");
-    CHECK_ERROR_PARAMS("326", 1, 3);
-    RECV(":server 326 alice bob");
-    CHECK_ERROR_PARAMS("326", 2, 3);
+    CHECK_ERROR_PARAMS("326", 1, 2);
     RECV(":server 335");
-    CHECK_ERROR_PARAMS("335", 0, 3);
+    CHECK_ERROR_PARAMS("335", 0, 2);
     RECV(":server 335 alice");
-    CHECK_ERROR_PARAMS("335", 1, 3);
-    RECV(":server 335 alice bob");
-    CHECK_ERROR_PARAMS("335", 2, 3);
+    CHECK_ERROR_PARAMS("335", 1, 2);
     RECV(":server 378");
-    CHECK_ERROR_PARAMS("378", 0, 3);
+    CHECK_ERROR_PARAMS("378", 0, 2);
     RECV(":server 378 alice");
-    CHECK_ERROR_PARAMS("378", 1, 3);
-    RECV(":server 378 alice bob");
-    CHECK_ERROR_PARAMS("378", 2, 3);
+    CHECK_ERROR_PARAMS("378", 1, 2);
     RECV(":server 379");
-    CHECK_ERROR_PARAMS("379", 0, 3);
+    CHECK_ERROR_PARAMS("379", 0, 2);
     RECV(":server 379 alice");
-    CHECK_ERROR_PARAMS("379", 1, 3);
-    RECV(":server 379 alice bob");
-    CHECK_ERROR_PARAMS("379", 2, 3);
+    CHECK_ERROR_PARAMS("379", 1, 2);
     RECV(":server 671");
-    CHECK_ERROR_PARAMS("671", 0, 3);
+    CHECK_ERROR_PARAMS("671", 0, 2);
     RECV(":server 671 alice");
-    CHECK_ERROR_PARAMS("671", 1, 3);
-    RECV(":server 671 alice bob");
-    CHECK_ERROR_PARAMS("671", 2, 3);
+    CHECK_ERROR_PARAMS("671", 1, 2);
 
     RECV(":server 223 alice bob UTF-8");
     CHECK_SRV("-- [bob] UTF-8");
     RECV(":server 223 alice bob :UTF-8");
     CHECK_SRV("-- [bob] UTF-8");
+    RECV(":server 223 alice bob");
+    CHECK_SRV("-- bob");
     RECV(":server 264 alice bob :is using encrypted connection");
     CHECK_SRV("-- [bob] is using encrypted connection");
+    RECV(":server 264 alice bob");
+    CHECK_SRV("-- bob");
     RECV(":server 275 alice bob :is using secure connection");
     CHECK_SRV("-- [bob] is using secure connection");
+    RECV(":server 275 alice bob");
+    CHECK_SRV("-- bob");
     RECV(":server 276 alice bob :has client certificate fingerprint");
     CHECK_SRV("-- [bob] has client certificate fingerprint");
+    RECV(":server 276 alice bob");
+    CHECK_SRV("-- bob");
     RECV(":server 307 alice bob :registered nick");
     CHECK_SRV("-- [bob] registered nick");
+    RECV(":server 307 alice bob");
+    CHECK_SRV("-- bob");
     RECV(":server 310 alice bob :help mode");
     CHECK_SRV("-- [bob] help mode");
+    RECV(":server 310 alice bob");
+    CHECK_SRV("-- bob");
     RECV(":server 313 alice bob :operator");
     CHECK_SRV("-- [bob] operator");
+    RECV(":server 313 alice bob");
+    CHECK_SRV("-- bob");
     RECV(":server 318 alice bob :end");
     CHECK_SRV("-- [bob] end");
+    RECV(":server 318 alice bob");
+    CHECK_SRV("-- bob");
     RECV(":server 319 alice bob :channels");
     CHECK_SRV("-- [bob] channels");
+    RECV(":server 319 alice bob");
+    CHECK_SRV("-- bob");
     RECV(":server 320 alice bob :identified user");
     CHECK_SRV("-- [bob] identified user");
+    RECV(":server 320 alice bob");
+    CHECK_SRV("-- bob");
     RECV(":server 326 alice bob :has oper privs");
     CHECK_SRV("-- [bob] has oper privs");
+    RECV(":server 326 alice bob");
+    CHECK_SRV("-- bob");
     RECV(":server 335 alice bob :is a bot");
     CHECK_SRV("-- [bob] is a bot");
+    RECV(":server 335 alice bob");
+    CHECK_SRV("-- bob");
+    RECV(":server 378 alice bob");
+    CHECK_SRV("-- bob");
     RECV(":server 378 alice bob :connecting from");
     CHECK_SRV("-- [bob] connecting from");
+    RECV(":server 378 alice bob");
+    CHECK_SRV("-- bob");
     RECV(":server 379 alice bob :using modes");
     CHECK_SRV("-- [bob] using modes");
+    RECV(":server 379 alice bob");
+    CHECK_SRV("-- bob");
     RECV(":server 671 alice bob :secure connection");
     CHECK_SRV("-- [bob] secure connection");
+    RECV(":server 671 alice bob");
+    CHECK_SRV("-- bob");
 }
 
 /*
@@ -2377,16 +2379,16 @@ TEST(IrcProtocolWithServer, whowas_nick_msg)
 
     /* not enough parameters */
     RECV(":server 369");
-    CHECK_ERROR_PARAMS("369", 0, 3);
+    CHECK_ERROR_PARAMS("369", 0, 2);
     RECV(":server 369 alice");
-    CHECK_ERROR_PARAMS("369", 1, 3);
-    RECV(":server 369 alice bob");
-    CHECK_ERROR_PARAMS("369", 2, 3);
+    CHECK_ERROR_PARAMS("369", 1, 2);
 
     RECV(":server 369 alice bob end");
     CHECK_SRV("-- [bob] end");
     RECV(":server 369 alice bob :end");
     CHECK_SRV("-- [bob] end");
+    RECV(":server 369 alice bob");
+    CHECK_SRV("-- bob");
 }
 
 /*