diff --git a/lib/index.js b/lib/index.js
index <HASH>..<HASH> 100644
--- a/lib/index.js
+++ b/lib/index.js
@@ -23,7 +23,7 @@ async function run(req, res, fn, onError) {
     const val = await fn(req, res)
 
     // return a non-null value -> send with 200
-    if (null != val) {
+    if (null !== val && undefined !== val) {
       send(res, 200, val)
     }
   } catch (err) {
Use !== instead of !=

This seems to conflict with the project's styleguide.