diff --git a/demo/.npmrc b/demo/.npmrc
new file mode 100644
index 0000000..4fd0219
--- /dev/null
+++ b/demo/.npmrc
@@ -0,0 +1 @@
+engine-strict=true
\ No newline at end of file
diff --git a/demo/package.json b/demo/package.json
index aafb253..d72bfd4 100644
--- a/demo/package.json
+++ b/demo/package.json
@@ -16,5 +16,8 @@
     "dotenv": "^16.4.7",
     "prettier": "^3.5.3",
     "typescript": "5.8.2"
+  },
+  "engines": {
+    "node": ">=18"
   }
 }