diff --git a/util/sponsor/auth.go b/util/sponsor/auth.go
index 913e52dbd..0991a5bcf 100644
--- a/util/sponsor/auth.go
+++ b/util/sponsor/auth.go
@@ -36,9 +36,12 @@ var (
 	mu                            sync.RWMutex
 	Subject, Token, ActivationKey string
 	ExpiresAt                     time.Time
-	machineID                     = machine.ProtectedID("evcc-sponsor")
 )
 
+func machineID() string {
+	return machine.ProtectedID("evcc-sponsor")
+}
+
 const unavailable = "sponsorship unavailable"
 
 func IsAuthorized() bool {
@@ -68,7 +71,7 @@ func ActivateSponsorship(licenseKey, email string) (string, error) {
 	res, err := client.Activate(ctx, &pb.ActivateRequest{
 		Key:       licenseKey,
 		Email:     email,
-		MachineId: machineID,
+		MachineId: machineID(),
 	})
 
 	if err != nil {
diff --git a/util/sponsor/hardware.go b/util/sponsor/hardware.go
index 38a298da0..ae2c35642 100644
--- a/util/sponsor/hardware.go
+++ b/util/sponsor/hardware.go
@@ -39,7 +39,7 @@ func checkHardware(vendor string, metadata map[string]string) string {
 
 	client := pb.NewAuthClient(conn)
 	res, err := client.IsAuthorizedHardware(ctx, &pb.HardwareRequest{
-		MachineId: machineID,
+		MachineId: machineID(),
 		Vendor:    vendor,
 		Metadata:  metadata,
 	})