diff --git a/pkg/cache/file/file.go b/pkg/cache/file/file.go
index 423913f..d7f6022 100644
--- a/pkg/cache/file/file.go
+++ b/pkg/cache/file/file.go
@@ -39,6 +39,7 @@ func NewFileCache(dir string) (cache.Cache, error) {
 }
 
 // Store stores the object and returns the metadata
+// Fails if the object already exists
 func (f *Cache) Store(_ context.Context, id string, content io.Reader) (cache.Object, error) {
 	if id == "" {
 		return cache.Object{}, fmt.Errorf("%w id cannot be empty", cache.ErrCreatingObject)
@@ -49,6 +50,11 @@ func (f *Cache) Store(_ context.Context, id string, content io.Reader) (cache.Ob
 	}
 
 	objectDir := filepath.Join(f.dir, id)
+
+	if _, err := os.Stat(objectDir); !errors.Is(err, os.ErrNotExist) {
+		return cache.Object{}, fmt.Errorf("%w: object already exists %q", cache.ErrCreatingObject, id)
+	}
+
 	// TODO: check permissions
 	err := os.MkdirAll(objectDir, 0o750)
 	if err != nil {
diff --git a/pkg/cache/file/file_test.go b/pkg/cache/file/file_test.go
index 4353119..ad82486 100644
--- a/pkg/cache/file/file_test.go
+++ b/pkg/cache/file/file_test.go
@@ -56,8 +56,9 @@ func TestFileCacheStoreObject(t *testing.T) {
 					content: []byte("content"),
 				},
 			},
-			id:      "object",
-			content: []byte("new content"),
+			id:        "object",
+			content:   []byte("new content"),
+			expectErr: cache.ErrCreatingObject,
 		},
 		{
 			title:   "store empty object",