diff --git a/src/inet/linklayer/base/MacRelayUnitBase.cc b/src/inet/linklayer/base/MacRelayUnitBase.cc
index 95d6d5f7a035..61d2be864887 100644
--- a/src/inet/linklayer/base/MacRelayUnitBase.cc
+++ b/src/inet/linklayer/base/MacRelayUnitBase.cc
@@ -82,7 +82,7 @@ void MacRelayUnitBase::sendPacket(Packet *packet, const MacAddress& destinationA
     send(packet, "lowerLayerOut");
 }
 
-void MacRelayUnitBase::updatePeerAddress(NetworkInterface *incomingInterface, MacAddress sourceAddress, unsigned int vlanId)
+void MacRelayUnitBase::updatePeerAddress(NetworkInterface *incomingInterface, MacAddress sourceAddress, int vlanId)
 {
     if (!sourceAddress.isMulticast()) {
         EV_INFO << "Learning peer address" << EV_FIELD(sourceAddress) << EV_FIELD(incomingInterface) << EV_ENDL;
diff --git a/src/inet/linklayer/base/MacRelayUnitBase.h b/src/inet/linklayer/base/MacRelayUnitBase.h
index 0901182690ce..9c48f7283e26 100644
--- a/src/inet/linklayer/base/MacRelayUnitBase.h
+++ b/src/inet/linklayer/base/MacRelayUnitBase.h
@@ -36,7 +36,7 @@ class INET_API MacRelayUnitBase : public LayeredProtocolBase, public StringForma
     virtual bool isForwardingInterface(NetworkInterface *networkInterface) const { return !networkInterface->isLoopback() && networkInterface->isBroadcast(); }
     virtual void broadcastPacket(Packet *packet, const MacAddress& destinationAddress, NetworkInterface *incomingInterface);
     virtual void sendPacket(Packet *packet, const MacAddress& destinationAddress, NetworkInterface *outgoingInterface);
-    virtual void updatePeerAddress(NetworkInterface *incomingInterface, MacAddress sourceAddress, unsigned int vlanId);
+    virtual void updatePeerAddress(NetworkInterface *incomingInterface, MacAddress sourceAddress, int vlanId);
 
     //@{ for lifecycle:
     virtual void handleStartOperation(LifecycleOperation *operation) override {}
diff --git a/src/inet/linklayer/ethernet/common/MacRelayUnit.cc b/src/inet/linklayer/ethernet/common/MacRelayUnit.cc
index 60c6b97e0169..e6ee74786d89 100644
--- a/src/inet/linklayer/ethernet/common/MacRelayUnit.cc
+++ b/src/inet/linklayer/ethernet/common/MacRelayUnit.cc
@@ -28,7 +28,7 @@ void MacRelayUnit::handleLowerPacket(Packet *incomingPacket)
     auto interfaceInd = incomingPacket->getTag<InterfaceInd>();
     int incomingInterfaceId = interfaceInd->getInterfaceId();
     auto incomingInterface = interfaceTable->getInterfaceById(incomingInterfaceId);
-    unsigned int vlanId = 0;
+    int vlanId = -1;
     if (auto vlanInd = incomingPacket->findTag<VlanInd>())
         vlanId = vlanInd->getVlanId();
     EV_INFO << "Processing packet from network" << EV_FIELD(incomingInterface) << EV_FIELD(incomingPacket) << EV_ENDL;
diff --git a/src/inet/linklayer/ieee8021d/relay/Ieee8021dRelay.cc b/src/inet/linklayer/ieee8021d/relay/Ieee8021dRelay.cc
index df8dafbb22cc..eb7e503c9f09 100644
--- a/src/inet/linklayer/ieee8021d/relay/Ieee8021dRelay.cc
+++ b/src/inet/linklayer/ieee8021d/relay/Ieee8021dRelay.cc
@@ -58,7 +58,7 @@ void Ieee8021dRelay::handleLowerPacket(Packet *incomingPacket)
     auto interfaceInd = incomingPacket->getTag<InterfaceInd>();
     int incomingInterfaceId = interfaceInd->getInterfaceId();
     auto incomingInterface = interfaceTable->getInterfaceById(incomingInterfaceId);
-    unsigned int vlanId = 0;
+    int vlanId = -1;
     if (auto vlanInd = incomingPacket->findTag<VlanInd>())
         vlanId = vlanInd->getVlanId();
     EV_INFO << "Processing packet from network" << EV_FIELD(incomingInterface) << EV_FIELD(incomingPacket) << EV_ENDL;
@@ -205,7 +205,7 @@ bool Ieee8021dRelay::isForwardingInterface(NetworkInterface *networkInterface) c
     return (interfaceData == nullptr || interfaceData->isForwarding());
 }
 
-void Ieee8021dRelay::updatePeerAddress(NetworkInterface *incomingInterface, MacAddress sourceAddress, unsigned int vlanId)
+void Ieee8021dRelay::updatePeerAddress(NetworkInterface *incomingInterface, MacAddress sourceAddress, int vlanId)
 {
     const auto& interfaceData = incomingInterface->findProtocolData<Ieee8021dInterfaceData>();
     if (interfaceData == nullptr || interfaceData->isLearning())
diff --git a/src/inet/linklayer/ieee8021d/relay/Ieee8021dRelay.h b/src/inet/linklayer/ieee8021d/relay/Ieee8021dRelay.h
index e1661350c6a7..cbec55dca027 100644
--- a/src/inet/linklayer/ieee8021d/relay/Ieee8021dRelay.h
+++ b/src/inet/linklayer/ieee8021d/relay/Ieee8021dRelay.h
@@ -54,7 +54,7 @@ class INET_API Ieee8021dRelay : public MacRelayUnitBase
     virtual void handleUpperPacket(Packet *packet) override;
     virtual void handleLowerPacket(Packet *packet) override;
 
-    virtual void updatePeerAddress(NetworkInterface *incomingInterface, MacAddress sourceAddress, unsigned int vlanId) override;
+    virtual void updatePeerAddress(NetworkInterface *incomingInterface, MacAddress sourceAddress, int vlanId) override;
 
     virtual void sendUp(Packet *packet);
     virtual bool isForwardingInterface(NetworkInterface *networkInterface) const override;