diff --git a/src/frontend/apis/index.js b/src/frontend/apis/index.js
index a4b645c1349092762f160bd1c74eb79596bf6d79..2a1001c767a29cabc48d7a132060ed4a4c26cb16 100644
--- a/src/frontend/apis/index.js
+++ b/src/frontend/apis/index.js
@@ -76,6 +76,10 @@ const TracerApi = {
     key: 'markdown',
     method: 'set',
     args: [code],
+  }, {
+    key: null,
+    method: 'setRoot',
+    args: ['markdown'],
   }]),
   json: ({ code }) => new Promise(resolve => resolve(JSON.parse(code))),
   js: ({ code }, params, cancelToken) => new Promise((resolve, reject) => {