diff --git a/lib/esm-utils.js b/lib/esm-utils.js
index ecd9a1cefa..14a9c28fa8 100644
--- a/lib/esm-utils.js
+++ b/lib/esm-utils.js
@@ -73,6 +73,7 @@ exports.loadFilesAsync = async (files, preLoadFunc, postLoadFunc) => {
   }
 };
 
+/* istanbul ignore next */
 async function implementationOfRequireOrImportForUnstableEsm(file) {
   if (path.extname(file) === '.mjs') {
     return formattedImport(file);