diff --git a/src/ui/js/diff2html-ui-base.ts b/src/ui/js/diff2html-ui-base.ts
index 906b97d..5c6bf95 100644
--- a/src/ui/js/diff2html-ui-base.ts
+++ b/src/ui/js/diff2html-ui-base.ts
@@ -142,7 +142,6 @@ export class Diff2HtmlUI {
       // HACK: help Typescript know that `this.hljs` is defined since we already checked it
       if (this.hljs === null) return;
       const language = file.getAttribute('data-lang');
-      const hljsLanguage = language ? this.hljs.getLanguage(language) : undefined;
 
       // Collect all the code lines and execute the highlight on them
       const codeLines = file.querySelectorAll('.d2h-code-line-ctn');
@@ -157,7 +156,7 @@ export class Diff2HtmlUI {
 
         const result: HighlightResult = closeTags(
           this.hljs.highlight(text, {
-            language: hljsLanguage?.name || 'plaintext',
+            language: language || 'plaintext',
             ignoreIllegals: true,
           }),
         );