diff --git a/include/haproxy/mqtt-t.h b/include/haproxy/mqtt-t.h
index 9377021..710fd87 100644
--- a/include/haproxy/mqtt-t.h
+++ b/include/haproxy/mqtt-t.h
@@ -27,6 +27,7 @@
 /* MQTT protocol version
  * In MQTT 3.1.1, version is called "level"
  */
+#define MQTT_VERSION_3_1      3
 #define MQTT_VERSION_3_1_1    4
 #define MQTT_VERSION_5_0      5
 
diff --git a/reg-tests/converter/mqtt.vtc b/reg-tests/converter/mqtt.vtc
index ea2cbb4..9f7e6b1 100644
--- a/reg-tests/converter/mqtt.vtc
+++ b/reg-tests/converter/mqtt.vtc
@@ -42,6 +42,11 @@
     recv 22
     sendhex "21020000"
     expect_close
+
+    # MQTT 3.1 CONNECT packet (id: test_sub - username: test - passwd: passwd)
+    accept
+    recv 38
+    sendhex "20020000"
 } -start
 
 server s2 {
@@ -225,3 +230,9 @@
     recv 39
     expect_close
 } -run
+
+client c3_31_1 -connect ${h1_fe1_sock} {
+    # Valid MQTT 3.1 CONNECT packet (id: test_sub - username: test - passwd: passwd)
+    sendhex "102400064d514973647003c200000008746573745f7375620004746573740006706173737764"
+    recv 4
+} -run
\ No newline at end of file
diff --git a/src/mqtt.c b/src/mqtt.c
index 6624201..75759b7 100644
--- a/src/mqtt.c
+++ b/src/mqtt.c
@@ -40,14 +40,14 @@
 const struct ist mqtt_fields_string[MQTT_FN_ENTRIES] = {
 	[MQTT_FN_INVALID]                            = IST(""),
 
-	/* it's MQTT 3.1.1 and 5.0, those fields have no unique id, so we use strings */
+	/* it's MQTT 3.1, 3.1.1 and 5.0, those fields have no unique id, so we use strings */
 	[MQTT_FN_FLAGS]                              = IST("flags"),
-	[MQTT_FN_REASON_CODE]                        = IST("reason_code"),       /* MQTT 3.1.1: return_code */
+	[MQTT_FN_REASON_CODE]                        = IST("reason_code"),       /* MQTT 3.1 and 3.1.1: return_code */
 	[MQTT_FN_PROTOCOL_NAME]                      = IST("protocol_name"),
 	[MQTT_FN_PROTOCOL_VERSION]                   = IST("protocol_version"),  /* MQTT 3.1.1: protocol_level */
 	[MQTT_FN_CLIENT_IDENTIFIER]                  = IST("client_identifier"),
 	[MQTT_FN_WILL_TOPIC]                         = IST("will_topic"),
-	[MQTT_FN_WILL_PAYLOAD]                       = IST("will_payload"),      /* MQTT 3.1.1: will_message */
+	[MQTT_FN_WILL_PAYLOAD]                       = IST("will_payload"),      /* MQTT 3.1 and 3.1.1: will_message */
 	[MQTT_FN_USERNAME]                           = IST("username"),
 	[MQTT_FN_PASSWORD]                           = IST("password"),
 	[MQTT_FN_KEEPALIVE]                          = IST("keepalive"),
@@ -695,6 +695,7 @@
 }
 
 /* Parses a CONNECT packet :
+ *   https://public.dhe.ibm.com/software/dw/webservices/ws-mqtt/mqtt-v3r1.html#connect
  *   https://docs.oasis-open.org/mqtt/mqtt/v3.1.1/os/mqtt-v3.1.1-os.html#_Toc398718028
  *   https://docs.oasis-open.org/mqtt/mqtt/v5.0/os/mqtt-v5.0-os.html#_Toc3901033
  *
@@ -718,14 +719,15 @@
 	 */
 	/* read protocol_name */
 	parser = mqtt_read_string(parser, &mpkt->data.connect.var_hdr.protocol_name);
-	if (!isttest(parser) || !isteqi(mpkt->data.connect.var_hdr.protocol_name, ist("MQTT")))
+	if (!isttest(parser) || !(isteqi(mpkt->data.connect.var_hdr.protocol_name, ist("MQTT")) || isteqi(mpkt->data.connect.var_hdr.protocol_name, ist("MQIsdp"))))
 		goto end;
 
 	/* read protocol_version */
 	parser = mqtt_read_1byte_int(parser, &mpkt->data.connect.var_hdr.protocol_version);
 	if (!isttest(parser))
 		goto end;
-	if (mpkt->data.connect.var_hdr.protocol_version != MQTT_VERSION_3_1_1 &&
+	if (mpkt->data.connect.var_hdr.protocol_version != MQTT_VERSION_3_1 &&
+	    mpkt->data.connect.var_hdr.protocol_version != MQTT_VERSION_3_1_1 &&
 	    mpkt->data.connect.var_hdr.protocol_version != MQTT_VERSION_5_0)
 		goto end;