diff --git a/backend.go b/backend.go
index b72f604..298c57e 100644
--- a/backend.go
+++ b/backend.go
@@ -321,7 +321,7 @@ type MultipartBackend interface {
 	ListParts(ctx context.Context, bucket, object string, uploadID UploadID, marker int, limit int64) (*ListMultipartUploadPartsResult, error)
 
 	AbortMultipartUpload(ctx context.Context, bucket, object string, id UploadID) error
-	CompleteMultipartUpload(ctx context.Context, bucket, object string, id UploadID, input *CompleteMultipartUploadRequest) (*CompleteMultipartUploadResult, error)
+	CompleteMultipartUpload(ctx context.Context, bucket, object string, id UploadID, meta map[string]string, input *CompleteMultipartUploadRequest) (*CompleteMultipartUploadResult, error)
 }
 
 type AuthenticatedBackend interface {
diff --git a/gofakes3.go b/gofakes3.go
index 98e4dc5..d0189b0 100644
--- a/gofakes3.go
+++ b/gofakes3.go
@@ -970,7 +970,12 @@ func (g *GoFakeS3) completeMultipartUpload(bucket, object string, uploadID Uploa
 		return err
 	}
 
-	res, err := g.uploader.CompleteMultipartUpload(r.Context(), bucket, object, uploadID, &in)
+	meta, err := metadataHeaders(r.Header, g.timeSource.Now(), g.metadataSizeLimit)
+	if err != nil {
+		return err
+	}
+
+	res, err := g.uploader.CompleteMultipartUpload(r.Context(), bucket, object, uploadID, meta, &in)
 	if err != nil {
 		return err
 	}
diff --git a/uploader.go b/uploader.go
index c4f4718..6536b5f 100644
--- a/uploader.go
+++ b/uploader.go
@@ -404,12 +404,16 @@ func (u *uploader) UploadPart(_ context.Context, bucket, object string, id Uploa
 	return &UploadPartResult{ETag: etag}, nil
 }
 
-func (u *uploader) CompleteMultipartUpload(ctx context.Context, bucket, object string, id UploadID, input *CompleteMultipartUploadRequest) (*CompleteMultipartUploadResult, error) {
+func (u *uploader) CompleteMultipartUpload(ctx context.Context, bucket, object string, id UploadID, meta map[string]string, input *CompleteMultipartUploadRequest) (*CompleteMultipartUploadResult, error) {
 	mpu, err := u.getUnlocked(bucket, object, id)
 	if err != nil {
 		return nil, err
 	}
 
+	for k, v := range meta {
+		mpu.Meta[k] = v
+	}
+
 	mpu.mu.Lock()
 	defer mpu.mu.Unlock()