diff --git a/packages/ui-default/package.json b/packages/ui-default/package.json
index 043a2ed9b..21f6245ea 100644
--- a/packages/ui-default/package.json
+++ b/packages/ui-default/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@hydrooj/ui-default",
-  "version": "4.7.4",
+  "version": "4.7.5",
   "author": "undefined <i@undefined.moe>",
   "license": "AGPL-3.0",
   "main": "hydro.js",
diff --git a/packages/ui-default/pages/problem_files.page.js b/packages/ui-default/pages/problem_files.page.js
index 46091fe63..b37135856 100644
--- a/packages/ui-default/pages/problem_files.page.js
+++ b/packages/ui-default/pages/problem_files.page.js
@@ -11,12 +11,12 @@ import tpl from 'vj/utils/tpl';
 import delay from 'vj/utils/delay';
 import i18n from 'vj/utils/i18n';
 
-try {
-  // Firefox have no WritableStream
-  if (!window.WritableStream) streamsaver.WritableStream = WritableStream;
+// Firefox have no WritableStream
+if (!window.WritableStream) streamsaver.WritableStream = WritableStream;
+if (window.location.protocol === 'https:'
+  || window.location.protocol === 'chrome-extension:'
+  || window.location.hostname === 'localhost') {
   streamsaver.mitm = '/streamsaver/mitm.html';
-} catch (e) {
-  // Extending not allowed in snowpack
 }
 
 async function downloadProblemFilesAsArchive(type, files) {