diff --git a/base/optional.h b/base/optional.h
index 84b302e53079..10586d65f225 100644
--- a/base/optional.h
+++ b/base/optional.h
@@ -345,7 +345,7 @@ struct IsConvertibleFromOptional
     : std::integral_constant<
           bool,
           std::is_constructible<T, Optional<U>&>::value ||
-              std::is_constructible<T, const Optional<U>&>::value ||
+              // std::is_constructible<T, const Optional<U>&>::value ||
               std::is_constructible<T, Optional<U>&&>::value ||
               std::is_constructible<T, const Optional<U>&&>::value ||
               std::is_convertible<Optional<U>&, T>::value ||