diff --git a/src/Ast/Controller/AstDetailController.php b/src/Ast/Controller/AstDetailController.php
index 82189564a..8bfeff4ff 100644
--- a/src/Ast/Controller/AstDetailController.php
+++ b/src/Ast/Controller/AstDetailController.php
@@ -22,6 +22,7 @@ public function __invoke(string $hash): View
             'page_title' => 'Play with AST',
             'astRun' => $astRun,
             'inputFormContents' => $astRun->getContent(),
+            'codeMirror' => true,
         ]);
     }
 }