diff --git a/lib/web/note/util.ts b/lib/web/note/util.ts
index 09cd60e94..3dcb42941 100644
--- a/lib/web/note/util.ts
+++ b/lib/web/note/util.ts
@@ -47,7 +47,7 @@ export module NoteUtils {
     }
   }
 
-  export function newNote(req: any, res: Response, body: string) {
+  export function newNote(req: any, res: Response, body: string | null) {
     let owner = null;
     const noteId = req.params.noteId ? req.params.noteId : null;
     if (req.isAuthenticated()) {
diff --git a/tsconfig.json b/tsconfig.json
index e69515925..ef2dd7ee8 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -2,6 +2,7 @@
   "compilerOptions": {
     "outDir": "./built",
     "allowJs": true,
+    "strictNullChecks": true,
     "target": "es5",
     "module": "commonjs",
     "esModuleInterop": true