diff --git a/apps/web/src/components/editor/course-editor.tsx b/apps/web/src/components/editor/course-editor.tsx
index 6ccc5dd..6abaf65 100644
--- a/apps/web/src/components/editor/course-editor.tsx
+++ b/apps/web/src/components/editor/course-editor.tsx
@@ -94,7 +94,7 @@ export function CourseEditor({ content, onChange }: CourseEditorProps) {
     if (!editorRef.current) return;
     const mermaidNodes = editorRef.current.querySelectorAll('pre[data-language="mermaid"]');
     if (mermaidNodes.length === 0) return;
-    mermaid.run({ nodes: Array.from(mermaidNodes), suppressErrors: true }).catch(() => {});
+    mermaid.run({ nodes: Array.from(mermaidNodes) as HTMLElement[], suppressErrors: true }).catch(() => {});
   }, [content]);
 
   const setLink = useCallback(() => {