diff --git a/apps/backend/src/app/storage/storage.service.ts b/apps/backend/src/app/storage/storage.service.ts
index 1ab28d3..f0f6382 100644
--- a/apps/backend/src/app/storage/storage.service.ts
+++ b/apps/backend/src/app/storage/storage.service.ts
@@ -31,7 +31,7 @@ export class StorageService {
 	 * @param {Buffer} file - The file for which the checksum is to be calculated.
 	 * @return {string} - The hexadecimal representation of the checksum.
 	 */
-	private getChecksum(file: Buffer) {
+	private getChecksum(file: Buffer): string {
 		return crypto.createHash('sha256').update(file).digest('hex').toLowerCase();
 	}