diff --git a/src/services/fileService.js b/src/services/fileService.js
index 99a7869..f66bf22 100644
--- a/src/services/fileService.js
+++ b/src/services/fileService.js
@@ -8,7 +8,7 @@ import validateAudioFile from '../utils/validateAudioFiles.js';
  */
 export default async function validateAudioFiles(filePaths) {
   // Validate input type
-  if (!filePaths instanceof Array) {
+  if (!(filePaths instanceof Array)) {
     throw new TypeError('Input must be an array of file paths (strings).');
   }
   // Create a Promise for each file to validate it as an audio file