diff --git a/index.html b/index.html
index 9945064..91d4877 100644
--- a/index.html
+++ b/index.html
@@ -110,8 +110,9 @@
                     .then(res => res.ok ? res.json() : Promise.reject(new Error(`Server responded ${res.status}`)))
                     .then(data => (status.textContent = 'Downloading file...', fetch(data.current_version.file.url).then(res => res.ok ? res.blob() : Promise.reject(new Error(`File download failed: ${res.status}`))).then(blob => ({blob, url: data.current_version.file.url}))))
                     .then(({blob, url}) => {
-                        const a = document.createElement('a'), fileName = url.split('/').pop().replace(/\.xpi$/, '.zip');
-                        a.href = URL.createObjectURL(blob);
+                        const zipBlob = new Blob([blob], { type: 'application/zip' }), fileName = url.split('/').pop().replace(/\.xpi$/, '.zip');
+                        const a = document.createElement('a');
+                        a.href = URL.createObjectURL(zipBlob);
                         a.download = fileName;
                         document.body.appendChild(a).click();
                         URL.revokeObjectURL(a.href);