diff --git a/src/drivers/uavcan_v1/Publishers/Gnss.hpp b/src/drivers/uavcan_v1/Publishers/Gnss.hpp
index b4dbd5ddc5..b728161704 100644
--- a/src/drivers/uavcan_v1/Publishers/Gnss.hpp
+++ b/src/drivers/uavcan_v1/Publishers/Gnss.hpp
@@ -59,7 +59,7 @@ public:
 	// Update the uORB Subscription and broadcast a UAVCAN message
 	virtual void update() override
 	{
-		if (_gps_sub.updated() && _port_id > 0) {
+		if (_gps_sub.updated() && _port_id != CANARD_PORT_ID_UNSET) {
 			sensor_gps_s gps {};
 			_gps_sub.update(&gps);
 
diff --git a/src/drivers/uavcan_v1/Publishers/Publisher.hpp b/src/drivers/uavcan_v1/Publishers/Publisher.hpp
index 2c81ecd464..2369aa24c0 100644
--- a/src/drivers/uavcan_v1/Publishers/Publisher.hpp
+++ b/src/drivers/uavcan_v1/Publishers/Publisher.hpp
@@ -53,6 +53,8 @@
 class UavcanPublication
 {
 public:
+	static constexpr uint16_t CANARD_PORT_ID_UNSET = 65535U;
+
 	UavcanPublication(CanardInstance &ins, UavcanParamManager &pmgr, const char *uavcan_pname) :
 		_canard_instance(ins), _param_manager(pmgr), _uavcan_param(uavcan_pname) { };
 
@@ -69,7 +71,7 @@ public:
 		int32_t new_id = value.integer32.value.elements[0];
 
 		if (_port_id != new_id) {
-			if (new_id == 0) {
+			if (new_id == CANARD_PORT_ID_UNSET) {
 				PX4_INFO("Disabling publication of %s", _uavcan_param);
 
 			} else {
@@ -81,7 +83,7 @@ public:
 
 	void printInfo()
 	{
-		if (_port_id > 0) {
+		if (_port_id != CANARD_PORT_ID_UNSET) {
 			PX4_INFO("Enabled %s on port %d", _uavcan_param, _port_id);
 		}
 	}
@@ -92,6 +94,6 @@ protected:
 	CanardRxSubscription _canard_sub;
 	const char *_uavcan_param; // Port ID parameter
 
-	CanardPortID _port_id {0};
+	CanardPortID _port_id {CANARD_PORT_ID_UNSET};
 	CanardTransferID _transfer_id {0};
 };
diff --git a/src/drivers/uavcan_v1/Subscribers/Subscriber.hpp b/src/drivers/uavcan_v1/Subscribers/Subscriber.hpp
index 9fe4fdda34..25c69dd519 100644
--- a/src/drivers/uavcan_v1/Subscribers/Subscriber.hpp
+++ b/src/drivers/uavcan_v1/Subscribers/Subscriber.hpp
@@ -53,6 +53,8 @@
 class UavcanSubscription
 {
 public:
+	static constexpr uint16_t CANARD_PORT_ID_UNSET = 65535U;
+
 	UavcanSubscription(CanardInstance &ins, UavcanParamManager &pmgr, const char *uavcan_pname) :
 		_canard_instance(ins), _param_manager(pmgr), _uavcan_param(uavcan_pname) { };
 
@@ -71,12 +73,12 @@ public:
 		int32_t new_id = value.integer32.value.elements[0];
 
 		if (_port_id != new_id) {
-			if (new_id == 0) {
+			if (new_id == CANARD_PORT_ID_UNSET) {
 				// Cancel subscription
 				unsubscribe();
 
 			} else {
-				if (_port_id > 0) {
+				if (_port_id != CANARD_PORT_ID_UNSET) {
 					// Already active; unsubscribe first
 					unsubscribe();
 				}
@@ -91,7 +93,7 @@ public:
 
 	void printInfo()
 	{
-		if (_port_id > 0) {
+		if (_port_id != CANARD_PORT_ID_UNSET) {
 			PX4_INFO("Subscribed %s on port %d", _uavcan_param, _port_id);
 		}
 	}
@@ -103,5 +105,5 @@ protected:
 	const char *_uavcan_param; // Port ID parameter
 	/// TODO: 'type' parameter? uavcan.pub.PORT_NAME.type (see 384.Access.1.0.uavcan)
 
-	CanardPortID _port_id {0};
+	CanardPortID _port_id {CANARD_PORT_ID_UNSET};
 };