diff --git a/gulpfile.esm.js/dev.js b/gulpfile.esm.js/dev.js
index 1d3641dea2f2b7d776c3d96d0b44673c674c0fc2..a47ddd26e3a4311e00ddf33a773ad3cb354cbbb3 100644
--- a/gulpfile.esm.js/dev.js
+++ b/gulpfile.esm.js/dev.js
@@ -9,7 +9,10 @@ const serve = () => {
     server({
       host: process.env.SERVER_HOST || "localhost",
       port: process.env.SERVER_PORT || 3000,
-      livereload: true,
+      livereload: {
+        enable: true,
+        filter: (filename, cb) => cb(!/(node_modules|\.pdf)$/.test(filename))
+      }
     })
   );
 };