diff --git a/cmd/restic/lock.go b/cmd/restic/lock.go
index a1b6ad5cb..38fc79a0c 100644
--- a/cmd/restic/lock.go
+++ b/cmd/restic/lock.go
@@ -16,7 +16,7 @@ func internalOpenWithLocked(ctx context.Context, gopts global.Options, dryRun bo
 
 	unlock := func() {}
 	if !dryRun {
-		var lock *repository.Unlocker
+		var lock repository.Unlocker
 
 		lock, ctx, err = repository.Lock(ctx, repo, exclusive, gopts.RetryLock, func(msg string) {
 			if !gopts.JSON {
diff --git a/internal/repository/lock.go b/internal/repository/lock.go
index a50195233..d794f03e7 100644
--- a/internal/repository/lock.go
+++ b/internal/repository/lock.go
@@ -37,13 +37,13 @@ var lockerInst = &locker{
 	refreshabilityTimeout: restic.StaleLockTimeout - defaultRefreshInterval*3/2,
 }
 
-func Lock(ctx context.Context, repo *Repository, exclusive bool, retryLock time.Duration, printRetry func(msg string), logger func(format string, args ...interface{})) (*Unlocker, context.Context, error) {
+func Lock(ctx context.Context, repo *Repository, exclusive bool, retryLock time.Duration, printRetry func(msg string), logger func(format string, args ...interface{})) (Unlocker, context.Context, error) {
 	return lockerInst.Lock(ctx, repo, exclusive, retryLock, printRetry, logger)
 }
 
 // Lock wraps the ctx such that it is cancelled when the repository is unlocked
 // cancelling the original context also stops the lock refresh
-func (l *locker) Lock(ctx context.Context, r *Repository, exclusive bool, retryLock time.Duration, printRetry func(msg string), logger func(format string, args ...interface{})) (*Unlocker, context.Context, error) {
+func (l *locker) Lock(ctx context.Context, r *Repository, exclusive bool, retryLock time.Duration, printRetry func(msg string), logger func(format string, args ...interface{})) (Unlocker, context.Context, error) {
 	var lock *restic.Lock
 	var err error
 
@@ -102,7 +102,7 @@ retryLoop:
 	go l.refreshLocks(ctx, repo.be, lockInfo, refreshChan, forceRefreshChan, logger)
 	go l.monitorLockRefresh(ctx, lockInfo, refreshChan, forceRefreshChan, logger)
 
-	return &Unlocker{lockInfo}, ctx, nil
+	return &unlocker{lockInfo}, ctx, nil
 }
 
 func minDuration(a, b time.Duration) time.Duration {
@@ -261,11 +261,15 @@ func tryRefreshStaleLock(ctx context.Context, be backend.Backend, lock *restic.L
 	return true
 }
 
-type Unlocker struct {
+type Unlocker interface {
+	Unlock()
+}
+
+type unlocker struct {
 	info *lockContext
 }
 
-func (l *Unlocker) Unlock() {
+func (l *unlocker) Unlock() {
 	l.info.cancel()
 	l.info.refreshWG.Wait()
 }
diff --git a/internal/repository/lock_test.go b/internal/repository/lock_test.go
index c31221e42..bdfb6573b 100644
--- a/internal/repository/lock_test.go
+++ b/internal/repository/lock_test.go
@@ -34,11 +34,11 @@ func openLockTestRepo(t *testing.T, wrapper backendWrapper) (*Repository, backen
 	return TestOpenBackend(t, be), be
 }
 
-func checkedLockRepo(ctx context.Context, t *testing.T, repo *Repository, lockerInst *locker, retryLock time.Duration) (*Unlocker, context.Context) {
+func checkedLockRepo(ctx context.Context, t *testing.T, repo *Repository, lockerInst *locker, retryLock time.Duration) (Unlocker, context.Context) {
 	lock, wrappedCtx, err := lockerInst.Lock(ctx, repo, false, retryLock, func(msg string) {}, func(format string, args ...interface{}) {})
 	rtest.OK(t, err)
 	rtest.OK(t, wrappedCtx.Err())
-	if lock.info.lock.Stale() {
+	if lock.(*unlocker).info.lock.Stale() {
 		t.Fatal("lock returned stale lock")
 	}
 	return lock, wrappedCtx