diff --git a/externs/mapfish-print-v3.js b/externs/mapfish-print-v3.js
index c4b09775978..3f1dab21424 100644
--- a/externs/mapfish-print-v3.js
+++ b/externs/mapfish-print-v3.js
@@ -44,6 +44,11 @@ let MapFishPrintAttributes = function() {};
 MapFishPrintAttributes.prototype.map;
 
 
+/**
+ * @type {Array.<Object>}
+ */
+MapFishPrintAttributes.prototype.datasource;
+
 
 /**
  * @constructor