diff --git a/lib/cli/run-option-metadata.js b/lib/cli/run-option-metadata.js
index 7deda70784..0ce34c986c 100644
--- a/lib/cli/run-option-metadata.js
+++ b/lib/cli/run-option-metadata.js
@@ -110,6 +110,7 @@ exports.isMochaFlag = flag => {
  * Returns expected yarg option type for a given mocha flag.
  * @param {string} flag - Flag to check (can be with out without leading "--"")
  * @returns {string | undefined} - If flag is a valid mocha flag, the expected type of argument for this flag is returned, otherwise undefined is returned.
+ * @private
  */
 exports.expectedTypeForFlag = flag => {
   const normalizedName = flag?.replace(/^--?/, '');