diff --git a/ui/Mainframe.tsx b/ui/Mainframe.tsx
index 5e2fcbf..6f6102d 100644
--- a/ui/Mainframe.tsx
+++ b/ui/Mainframe.tsx
@@ -136,7 +136,7 @@ export const Mainframe = <RS extends {}>({ langName, provider }: Props<RS>) => {
       renderEditor={() => (
         <CodeEditor
           ref={codeEditorRef}
-          languageId="brainfuck"
+          languageId={langName}
           readOnly={execController.state === "processing"}
           defaultValue={providerRef.current.sampleProgram}
           tokensProvider={providerRef.current.editorTokensProvider}
diff --git a/ui/code-editor/index.tsx b/ui/code-editor/index.tsx
index 473f44a..41cfcdc 100644
--- a/ui/code-editor/index.tsx
+++ b/ui/code-editor/index.tsx
@@ -98,7 +98,7 @@ const CodeEditorComponent = (props: Props, ref: React.Ref<CodeEditorRef>) => {
   return (
     <Editor
       theme={isDark ? "ep-dark" : "ep-light"}
-      defaultLanguage="brainfuck"
+      defaultLanguage={props.languageId}
       defaultValue={props.defaultValue}
       beforeMount={(monaco) => {
         monaco.editor.defineTheme("ep-dark", darkTheme as any);