diff --git a/externs/olx.js b/externs/olx.js
index 7fc47e1e01..dc251060d5 100644
--- a/externs/olx.js
+++ b/externs/olx.js
@@ -5855,6 +5855,7 @@ olx.source.WMTSOptions.prototype.wrapX;
  * @typedef {{attributions: (Array.<ol.Attribution>|undefined),
  *     crossOrigin: (null|string|undefined),
  *     logo: (string|olx.LogoOptions|undefined),
+ *     opaque: (boolean|undefined),
  *     projection: ol.proj.ProjectionLike,
  *     reprojectionErrorThreshold: (number|undefined),
  *     maxZoom: (number|undefined),
@@ -5900,6 +5901,14 @@ olx.source.XYZOptions.prototype.crossOrigin;
 olx.source.XYZOptions.prototype.logo;
 
 
+/**
+ * Whether the layer is opaque.
+ * @type {boolean|undefined}
+ * @api
+ */
+olx.source.XYZOptions.prototype.opaque;
+
+
 /**
  * Projection. Default is `EPSG:3857`.
  * @type {ol.proj.ProjectionLike}