diff --git a/include/pybind11/cast.h b/include/pybind11/cast.h
index a0b83ab625..e41ad2abfa 100644
--- a/include/pybind11/cast.h
+++ b/include/pybind11/cast.h
@@ -743,6 +743,7 @@ class type_caster<std::tuple<Ts...>> : public tuple_caster<std::tuple, Ts...> {}
 template <>
 class type_caster<std::tuple<>> : public tuple_caster<std::tuple> {
 public:
+    // PEP 484 specifies this syntax for an empty tuple
     static constexpr auto name = const_name("tuple[()]");
 };