2 files changed, 10 insertions, 5 deletions
diff --git a/internal/feed/cache/cache.go b/internal/feed/cache/cache.go
index e69e8f3..3a80df1 100644
--- a/internal/feed/cache/cache.go
+++ b/internal/feed/cache/cache.go
@@ -18,12 +18,12 @@ import (
 type Version byte
 
 const (
-	currentVersion Version = 1
+	currentVersion Version = v1Version
 )
 
 type Impl interface {
 	cachedFeed(*feed.Feed) CachedFeed
-	transformToCurrent() (Impl, error)
+	transformTo(Version) (Impl, error)
 	Version() Version
 	Info() string
 	SpecificInfo(interface{}) string
@@ -169,7 +169,7 @@ func Load(fileName string) (Cache, error) {
 		return Cache{}, fmt.Errorf("decoding for version '%d' from '%s': %w", version, fileName, err)
 	}
 
-	if cache, err = cache.transformToCurrent(); err != nil {
+	if cache, err = cache.transformTo(currentVersion); err != nil {
 		return Cache{}, fmt.Errorf("cannot transform from version %d to %d: %w", version, currentVersion, err)
 	}
 
diff --git a/internal/feed/cache/cache_v1.go b/internal/feed/cache/cache_v1.go
index cef26f6..7d95d4c 100644
--- a/internal/feed/cache/cache_v1.go
+++ b/internal/feed/cache/cache_v1.go
@@ -175,8 +175,13 @@ func newV1Cache() *v1Cache {
 	return &cache
 }
 
-func (cache *v1Cache) transformToCurrent() (Impl, error) {
-	return cache, nil
+func (cache *v1Cache) transformTo(v Version) (Impl, error) {
+	switch v {
+	case v1Version:
+		return cache, nil
+	default:
+		return nil, fmt.Errorf("Transformation not supported")
+	}
 }
 
 func (cache *v1Cache) getItem(id feedId) *cachedFeed {