diff --git a/externs/olx.js b/externs/olx.js
index 75a1d4d50f..b527195d2f 100644
--- a/externs/olx.js
+++ b/externs/olx.js
@@ -1757,7 +1757,7 @@ olx.format.PolylineOptions;
 /**
  * The factor by which the coordinates values will be scaled.
  * Default is `1e5`.
- * @type {number}
+ * @type {number|undefined}
  * @api stable
  */
 olx.format.PolylineOptions.prototype.factor;