diff --git a/include/pybind11/cast.h b/include/pybind11/cast.h
index 3d30ff37a..6a5ef1543 100644
--- a/include/pybind11/cast.h
+++ b/include/pybind11/cast.h
@@ -1379,7 +1379,8 @@ obj_attr_accessor object_api<D>::attr_with_type_hint(handle key) const {
     object ann = annotations();
     object reinterpreted_key = reinterpret_borrow<object>(key);
     if (ann.contains(reinterpreted_key)) {
-        throw std::runtime_error("__annotations__[\"" + std::string(py::str(reinterpreted_key)) + "\"] was set already.");
+        throw std::runtime_error("__annotations__[\"" + std::string(py::str(reinterpreted_key))
+                                 + "\"] was set already.");
     }
     ann[key] = make_caster<T>::name.text;
     return {derived(), reinterpreted_key};