diff --git a/lib/build.js b/lib/build.js
index 764dad09..66ec33fd 100644
--- a/lib/build.js
+++ b/lib/build.js
@@ -82,6 +82,17 @@ function webpackConfig(dir, additionalConfig) {
       webpackConfig.entry[name] = "./" + file;
     }
   });
+  if (Object.keys(webpackConfig.entry) < 1) {
+    console.warn(
+      `
+      ---Start netlify-lambda notification---
+      WARNING: No valid single functions files (ending in .mjs, .js or .ts) were found. 
+      This could be because you have nested them in a folder.
+      If this is expected (e.g. you have a zipped function built somewhere else), you may ignore this.
+      ---End netlify-lambda notification---
+      `
+    );
+  }
   if (additionalConfig) {
     var webpackAdditional = require(path.join(process.cwd(), additionalConfig));