diff --git a/tree-view-sample/package.json b/tree-view-sample/package.json
index 79915c9e..741fcd40 100644
--- a/tree-view-sample/package.json
+++ b/tree-view-sample/package.json
@@ -7,6 +7,7 @@
 	"engines": {
 		"vscode": "^1.20.0"
 	},
+	"enableProposedApi": true,
 	"categories": [
 		"Other"
 	],