diff --git a/externs/olx.js b/externs/olx.js
index 8578e054a1..8d94e6f8f6 100644
--- a/externs/olx.js
+++ b/externs/olx.js
@@ -3011,6 +3011,13 @@ olx.source.TileImageOptions.prototype.opaque;
 olx.source.TileImageOptions.prototype.projection;
 
 
+/**
+ * Source state.
+ * @type {ol.source.State|string|undefined}
+ */
+olx.source.TileImageOptions.prototype.state;
+
+
 /**
  * tile class
  * @type {function(new: ol.ImageTile, ol.TileCoord,