diff --git a/src/js/extendedFamilyModeJS.js b/src/js/extendedFamilyModeJS.js
index c467ec7bcb5b56fab5970e9e910ba256e1a11444..9ab734dfd28864e16f266cb1827f00fe78e56243 100644
--- a/src/js/extendedFamilyModeJS.js
+++ b/src/js/extendedFamilyModeJS.js
@@ -279,7 +279,7 @@ globalThis.mutualChildren = function(slave1, slave2, slaves) {
 
 /** Returns a random slave related to a given entity
  * @param {Relative} slave
- * @param {function(App.Entity.SlaveState): boolean} filterFunction
+ * @param {function(App.Entity.SlaveState): boolean} [filterFunction]
  * @returns {App.Entity.SlaveState}
  */
 globalThis.randomRelatedSlave = function(slave, filterFunction) {