diff --git a/README.md b/README.md
index 6bf7355..774f0c1 100644
--- a/README.md
+++ b/README.md
@@ -31,6 +31,7 @@ It supports the following environment variables - but these are a pain, the conf
 -   `MQTT_HOST` (optional, default = 'localhost')
 -   `MQTT_QOS` (optional, default = 0)
 -   `MQTT_PORT` (optional, default = 1883)
+-   `MQTT_PROTOCOL` (optional, default = '5') - MQTT protocol version: '3.1.1' or '5'
 -   `MQTT_TLS_ENABLED` (required if using TLS) - set to `true` to enable
 -   `MQTT_TLS_CA_CERT` (required if using TLS) - path to the ca certs
 -   `MQTT_TLS_CERT` (required if using TLS) - path to the private cert
diff --git a/config.yaml.sample b/config.yaml.sample
index 78b06ab..a1f6a86 100644
--- a/config.yaml.sample
+++ b/config.yaml.sample
@@ -4,6 +4,7 @@ mqtt:
   username: mqtt
   password: password
   qos: 0
+  protocol_version: "5"  # MQTT protocol version: "3.1.1" or "5" (default: "5")
   prefix: amcrest2mqtt
   discovery_prefix: homeassistant
   tls_enabled: False
diff --git a/src/amcrest2mqtt/mixins/helpers.py b/src/amcrest2mqtt/mixins/helpers.py
index 317246f..5aad5e7 100644
--- a/src/amcrest2mqtt/mixins/helpers.py
+++ b/src/amcrest2mqtt/mixins/helpers.py
@@ -200,6 +200,7 @@ class HelpersMixin:
             "host":             str(mqtt.get("host")             or os.getenv("MQTT_HOST", "localhost")),
             "port":         int(str(mqtt.get("port")             or os.getenv("MQTT_PORT", 1883))),
             "qos":          int(str(mqtt.get("qos")              or os.getenv("MQTT_QOS", 0))),
+            "protocol_version": str(mqtt.get("protocol_version", os.getenv("MQTT_PROTOCOL", "5"))),
             "username":         str(mqtt.get("username")         or os.getenv("MQTT_USERNAME", "")),
             "password":         str(mqtt.get("password")         or os.getenv("MQTT_PASSWORD", "")),
             "tls_enabled":     bool(mqtt.get("tls_enabled")      or (os.getenv("MQTT_TLS_ENABLED", "false").lower() == "true")),
diff --git a/uv.lock b/uv.lock
index 7778322..88563a4 100644
--- a/uv.lock
+++ b/uv.lock
@@ -464,7 +464,7 @@ sdist = { url = "https://files.pythonhosted.org/packages/93/4b/979db9e44be09f71e
 [[package]]
 name = "mqtt-helper-graystorm"
 version = "0.1.0"
-source = { git = "https://github.com/weirdtangent/mqtt-helper.git?branch=main#44eeeb0d2559cfa6ae141c623ecda72502a891e5" }
+source = { git = "https://github.com/weirdtangent/mqtt-helper.git?branch=main#58cd02c2c9675830feb5b433aff5b5a517572c56" }
 dependencies = [
     { name = "logging" },
     { name = "paho-mqtt" },