diff --git a/src/index.js b/src/index.js
index 7d3012a..6e88ee7 100644
--- a/src/index.js
+++ b/src/index.js
@@ -124,6 +124,7 @@ runButton.onclick = () => {
 
 function downloadFile(content, extension, mime) {
     const filename = prompt("Filename?");
+    if (filename === null) return;
 
     const blob = new Blob([content], { type: mime });
     const url = URL.createObjectURL(blob);