diff --git a/judgels-client/src/components/ProblemWorksheetCard/Programming/ProblemSubmissionEditor/ProblemSubmissionEditor.jsx b/judgels-client/src/components/ProblemWorksheetCard/Programming/ProblemSubmissionEditor/ProblemSubmissionEditor.jsx
index 4dcf51cf5..25c645a76 100644
--- a/judgels-client/src/components/ProblemWorksheetCard/Programming/ProblemSubmissionEditor/ProblemSubmissionEditor.jsx
+++ b/judgels-client/src/components/ProblemWorksheetCard/Programming/ProblemSubmissionEditor/ProblemSubmissionEditor.jsx
@@ -12,6 +12,7 @@ import {
   getGradingLanguageEditorSubmissionHint,
   gradingLanguageNamesMap,
 } from '../../../../modules/api/gabriel/language.js';
+import { decodeBase64 } from '../../../../utils/base64';
 
 import './ProblemSubmissionEditor.scss';
 
@@ -72,7 +73,7 @@ export function ProblemSubmissionEditor({
 
     (skeletons || []).forEach(skeleton => {
       if (skeleton.languages.indexOf(defaultGradingLanguage) >= 0) {
-        initialValues.editor = atob(skeleton.content);
+        initialValues.editor = decodeBase64(skeleton.content);
       }
     });
 
diff --git a/judgels-client/src/components/SubmissionDetails/Programming/SubmissionDetails.jsx b/judgels-client/src/components/SubmissionDetails/Programming/SubmissionDetails.jsx
index 96d97af92..64e302f9f 100644
--- a/judgels-client/src/components/SubmissionDetails/Programming/SubmissionDetails.jsx
+++ b/judgels-client/src/components/SubmissionDetails/Programming/SubmissionDetails.jsx
@@ -16,6 +16,7 @@ import {
 import { isInteractive, isOutputOnly } from '../../../modules/api/gabriel/engine';
 import { DEFAULT_SOURCE_KEY } from '../../../modules/api/gabriel/submission';
 import { VerdictCode } from '../../../modules/api/gabriel/verdict';
+import { decodeBase64 } from '../../../utils/base64';
 
 import './SubmissionDetails.scss';
 
@@ -301,7 +302,7 @@ export function SubmissionDetails({
           {key === DEFAULT_SOURCE_KEY ? '' : key + ': '} {submissionFiles[key].name}
         </h5>
         <SourceCode language={getGradingLanguageSyntaxHighlighterValue(gradingLanguage)}>
-          {atob(submissionFiles[key].content)}
+          {decodeBase64(submissionFiles[key].content)}
         </SourceCode>
         {verdict.code === VerdictCode.CE &&
           details &&
diff --git a/judgels-client/src/utils/base64.js b/judgels-client/src/utils/base64.js
new file mode 100644
index 000000000..099395b14
--- /dev/null
+++ b/judgels-client/src/utils/base64.js
@@ -0,0 +1,5 @@
+// https://developer.mozilla.org/en-US/docs/Glossary/Base64#the_unicode_problem
+export function decodeBase64(base64) {
+  const binString = atob(base64);
+  return new TextDecoder().decode(Uint8Array.from(binString, m => m.codePointAt(0)));
+}