diff --git a/include/pybind11/stl.h b/include/pybind11/stl.h
index 32f8d294a..77da13362 100644
--- a/include/pybind11/stl.h
+++ b/include/pybind11/stl.h
@@ -266,7 +266,8 @@ template<typename T> struct optional_caster {
     static handle cast(T_ &&src, return_value_policy policy, handle parent) {
         if (!src)
             return none().inc_ref();
-        policy = return_value_policy_override<typename T::value_type>::policy(policy);
+        using dereference_type = decltype(*std::forward<T_>(src));
+        policy = return_value_policy_override<dereference_type>::policy(policy);
         return value_conv::cast(*std::forward<T_>(src), policy, parent);
     }