diff --git a/jstree/jstree.d.ts b/jstree/jstree.d.ts
index d5641c8ba3..7d8561ed45 100644
--- a/jstree/jstree.d.ts
+++ b/jstree/jstree.d.ts
@@ -1,6 +1,6 @@
-// Type definitions for jsTree v3.0.0
+ï»ż// Type definitions for jsTree v3.0.0
 // Project: http://www.jstree.com/
-// Definitions by: Adam Pluciński <https://github.com/adaskothebeast>
+// Definitions by: Adam PluciƄski <https://github.com/adaskothebeast>
 // Definitions: https://github.com/borisyankov/DefinitelyTyped
 
 ///<reference path="../jquery/jquery.d.ts" />
@@ -508,7 +508,7 @@ interface JSTree extends JQuery {
     * @name destroy()
     * @param  {Boolean} keep_html if not set to `true` the container will be emptied, otherwise the current DOM elements will be kept intact
     */
-    destroy: (keep_html: boolean) => void;
+    destroy: (keep_html?: boolean) => void;
     /**
     * returns the jQuery extended instance container
     * @name get_container()