diff --git a/examples/vite-demo-vanilla-bundle/src/examples/example31.ts b/examples/vite-demo-vanilla-bundle/src/examples/example31.ts
index a20a8dd74..3d828be34 100644
--- a/examples/vite-demo-vanilla-bundle/src/examples/example31.ts
+++ b/examples/vite-demo-vanilla-bundle/src/examples/example31.ts
@@ -31,14 +31,16 @@ export default class Example31 {
   }
 
   handleFileImport(event: any) {
-    const file = event.target.files[0];
-    if (file) {
+    const file: File = event.target.files[0];
+    if (file.name.endsWith('.csv')) {
       const reader = new FileReader();
       reader.onload = (e: any) => {
         const content = e.target.result;
         this.dynamicallyCreateGrid(content);
       };
       reader.readAsText(file);
+    } else {
+      alert('File must be a CSV file');
     }
   }