diff --git a/cmd/tusd/cli/composer.go b/cmd/tusd/cli/composer.go
index aee2c68..6709ddc 100644
--- a/cmd/tusd/cli/composer.go
+++ b/cmd/tusd/cli/composer.go
@@ -5,6 +5,7 @@ import (
 	"path/filepath"
 
 	"github.com/tus/tusd/pkg/filestore"
+	"github.com/tus/tusd/pkg/gcsstore"
 	"github.com/tus/tusd/pkg/handler"
 	"github.com/tus/tusd/pkg/memorylocker"
 	"github.com/tus/tusd/pkg/s3store"
@@ -47,7 +48,7 @@ func CreateComposer() {
 			stderr.Fatalf("No service account file provided for Google Cloud Storage using the GCS_SERVICE_ACCOUNT_FILE environment variable.\n")
 		}
 
-		/*service, err := gcsstore.NewGCSService(gcsSAF)
+		service, err := gcsstore.NewGCSService(gcsSAF)
 		if err != nil {
 			stderr.Fatalf("Unable to create Google Cloud Storage service: %s\n", err)
 		}
@@ -59,7 +60,7 @@ func CreateComposer() {
 		store.UseIn(Composer)
 
 		locker := memorylocker.New()
-		locker.UseIn(Composer)*/
+		locker.UseIn(Composer)
 	} else {
 		dir, err := filepath.Abs(Flags.UploadDir)
 		if err != nil {
diff --git a/pkg/gcsstore/gcsstore.go b/pkg/gcsstore/gcsstore.go
index a4fe264..301b8ae 100644
--- a/pkg/gcsstore/gcsstore.go
+++ b/pkg/gcsstore/gcsstore.go
@@ -54,11 +54,9 @@ func New(bucket string, service GCSAPI) GCSStore {
 func (store GCSStore) UseIn(composer *handler.StoreComposer) {
 	composer.UseCore(store)
 	composer.UseTerminater(store)
-	composer.UseFinisher(store)
-	composer.UseGetReader(store)
 }
 
-func (store GCSStore) NewUpload(info handler.FileInfo) (id string, err error) {
+func (store GCSStore) NewUpload(info handler.FileInfo) (handler.Upload, error) {
 	if info.ID == "" {
 		info.ID = uid.Uid()
 	}
@@ -70,15 +68,31 @@ func (store GCSStore) NewUpload(info handler.FileInfo) (id string, err error) {
 	}
 
 	ctx := context.Background()
-	err = store.writeInfo(ctx, store.keyWithPrefix(info.ID), info)
+	err := store.writeInfo(ctx, store.keyWithPrefix(info.ID), info)
 	if err != nil {
-		return info.ID, err
+		return &gcsUpload{info.ID, &store}, err
 	}
 
-	return info.ID, nil
+	return &gcsUpload{info.ID, &store}, nil
 }
 
-func (store GCSStore) WriteChunk(id string, offset int64, src io.Reader) (int64, error) {
+type gcsUpload struct {
+	id    string
+	store *GCSStore
+}
+
+func (store GCSStore) GetUpload(id string) (handler.Upload, error) {
+	return &gcsUpload{id, &store}, nil
+}
+
+func (store GCSStore) AsTerminatableUpload(upload handler.Upload) handler.TerminatableUpload {
+	return upload.(*gcsUpload)
+}
+
+func (upload gcsUpload) WriteChunk(offset int64, src io.Reader) (int64, error) {
+	id := upload.id
+	store := upload.store
+
 	prefix := fmt.Sprintf("%s_", store.keyWithPrefix(id))
 	filterParams := GCSFilterParams{
 		Bucket: store.Bucket,
@@ -121,7 +135,10 @@ func (store GCSStore) WriteChunk(id string, offset int64, src io.Reader) (int64,
 
 const CONCURRENT_SIZE_REQUESTS = 32
 
-func (store GCSStore) GetInfo(id string) (handler.FileInfo, error) {
+func (upload gcsUpload) GetInfo() (handler.FileInfo, error) {
+	id := upload.id
+	store := upload.store
+
 	info := handler.FileInfo{}
 	i := fmt.Sprintf("%s.info", store.keyWithPrefix(id))
 
@@ -241,7 +258,10 @@ func (store GCSStore) writeInfo(ctx context.Context, id string, info handler.Fil
 	return nil
 }
 
-func (store GCSStore) FinishUpload(id string) error {
+func (upload gcsUpload) FinishUpload() error {
+	id := upload.id
+	store := upload.store
+
 	prefix := fmt.Sprintf("%s_", store.keyWithPrefix(id))
 	filterParams := GCSFilterParams{
 		Bucket: store.Bucket,
@@ -270,7 +290,7 @@ func (store GCSStore) FinishUpload(id string) error {
 		return err
 	}
 
-	info, err := store.GetInfo(id)
+	info, err := upload.GetInfo()
 	if err != nil {
 		return err
 	}
@@ -288,7 +308,10 @@ func (store GCSStore) FinishUpload(id string) error {
 	return nil
 }
 
-func (store GCSStore) Terminate(id string) error {
+func (upload gcsUpload) Terminate() error {
+	id := upload.id
+	store := upload.store
+
 	filterParams := GCSFilterParams{
 		Bucket: store.Bucket,
 		Prefix: store.keyWithPrefix(id),
@@ -303,7 +326,10 @@ func (store GCSStore) Terminate(id string) error {
 	return nil
 }
 
-func (store GCSStore) GetReader(id string) (io.Reader, error) {
+func (upload gcsUpload) GetReader() (io.Reader, error) {
+	id := upload.id
+	store := upload.store
+
 	params := GCSObjectParams{
 		Bucket: store.Bucket,
 		ID:     store.keyWithPrefix(id),
diff --git a/pkg/gcsstore/gcsstore_test.go b/pkg/gcsstore/gcsstore_test.go
index 8b0cc5e..25e9592 100644
--- a/pkg/gcsstore/gcsstore_test.go
+++ b/pkg/gcsstore/gcsstore_test.go
@@ -64,9 +64,9 @@ func TestNewUpload(t *testing.T) {
 	ctx := context.Background()
 	service.EXPECT().WriteObject(ctx, params, r).Return(int64(r.Len()), nil)
 
-	id, err := store.NewUpload(mockTusdInfo)
+	upload, err := store.NewUpload(mockTusdInfo)
 	assert.Nil(err)
-	assert.Equal(id, mockID)
+	assert.NotNil(upload)
 }
 
 func TestNewUploadWithPrefix(t *testing.T) {
@@ -99,9 +99,9 @@ func TestNewUploadWithPrefix(t *testing.T) {
 	ctx := context.Background()
 	service.EXPECT().WriteObject(ctx, params, r).Return(int64(r.Len()), nil)
 
-	id, err := store.NewUpload(mockTusdInfo)
+	upload, err := store.NewUpload(mockTusdInfo)
 	assert.Nil(err)
-	assert.Equal(id, mockID)
+	assert.NotNil(upload)
 }
 
 type MockGetInfoReader struct{}
@@ -185,7 +185,10 @@ func TestGetInfo(t *testing.T) {
 
 	service.EXPECT().WriteObject(ctx, params, infoR).Return(int64(len(offsetInfoData)), nil).After(lastGetObjectSize)
 
-	info, err := store.GetInfo(mockID)
+	upload, err := store.GetUpload(mockID)
+	assert.Nil(err)
+
+	info, err := upload.GetInfo()
 	assert.Nil(err)
 	assert.Equal(mockTusdInfo, info)
 
@@ -211,7 +214,10 @@ func TestGetInfoNotFound(t *testing.T) {
 		service.EXPECT().ReadObject(ctx, params).Return(nil, storage.ErrObjectNotExist),
 	)
 
-	_, err := store.GetInfo(mockID)
+	upload, err := store.GetUpload(mockID)
+	assert.Nil(err)
+
+	_, err = upload.GetInfo()
 	assert.Equal(handler.ErrNotFound, err)
 }
 
@@ -257,7 +263,11 @@ func TestGetReader(t *testing.T) {
 
 	ctx := context.Background()
 	service.EXPECT().ReadObject(ctx, params).Return(r, nil)
-	reader, err := store.GetReader(mockID)
+
+	upload, err := store.GetUpload(mockID)
+	assert.Nil(err)
+
+	reader, err := upload.GetReader()
 	assert.Nil(err)
 
 	buf := make([]byte, len(mockReaderData))
@@ -285,7 +295,10 @@ func TestTerminate(t *testing.T) {
 	ctx := context.Background()
 	service.EXPECT().DeleteObjectsWithFilter(ctx, filterParams).Return(nil)
 
-	err := store.Terminate(mockID)
+	upload, err := store.GetUpload(mockID)
+	assert.Nil(err)
+
+	err = store.AsTerminatableUpload(upload).Terminate()
 	assert.Nil(err)
 }
 
@@ -371,7 +384,10 @@ func TestFinishUpload(t *testing.T) {
 	writeObject := service.EXPECT().WriteObject(ctx, infoParams, infoR).Return(int64(len(offsetInfoData)), nil).After(lastGetObjectSize)
 	service.EXPECT().SetObjectMetadata(ctx, objectParams, metadata).Return(nil).After(writeObject)
 
-	err = store.FinishUpload(mockID)
+	upload, err := store.GetUpload(mockID)
+	assert.Nil(err)
+
+	err = upload.FinishUpload()
 	assert.Nil(err)
 
 	// Cancel the context to avoid getting an error from `go vet`
@@ -446,7 +462,11 @@ func TestWriteChunk(t *testing.T) {
 	reader := bytes.NewReader([]byte(mockReaderData))
 	var offset int64
 	offset = mockSize / 3
-	_, err := store.WriteChunk(mockID, offset, reader)
+
+	upload, err := store.GetUpload(mockID)
+	assert.Nil(err)
+
+	_, err = upload.WriteChunk(offset, reader)
 	assert.Nil(err)
 
 }