diff --git a/externs/olx.js b/externs/olx.js
index 09e1f63b39..82c3fde073 100644
--- a/externs/olx.js
+++ b/externs/olx.js
@@ -2659,6 +2659,15 @@ olx.interaction.DrawOptions.prototype.maxPoints;
 olx.interaction.DrawOptions.prototype.minPoints;
 
 
+/**
+ * A function that takes an {@link ol.MapBrowserEvent} and returns a boolean
+ * to indicate whether the drawing can be finished.
+ * @type {ol.events.ConditionType|undefined}
+ * @api
+ */
+olx.interaction.DrawOptions.prototype.finishCondition;
+
+
 /**
  * Style for sketch features.
  * @type {ol.style.Style|Array.<ol.style.Style>|ol.style.StyleFunction|undefined}