diff --git a/lib/esbonio/esbonio/server/features/sphinx_support/symbols.py b/lib/esbonio/esbonio/server/features/sphinx_support/symbols.py
index f4b4f6637..d0916e6b3 100644
--- a/lib/esbonio/esbonio/server/features/sphinx_support/symbols.py
+++ b/lib/esbonio/esbonio/server/features/sphinx_support/symbols.py
@@ -54,7 +54,7 @@ async def document_symbol(
                 if parent.children is None:
                     parent.children = [symbol]
                 else:
-                    parent.children.append(symbol)
+                    parent.children.append(symbol)  # type: ignore[attr-defined]
 
         return root