diff --git a/include/flux/op/cartesian_power_map.hpp b/include/flux/op/cartesian_power_map.hpp
index c2f8eb02..f41e3296 100644
--- a/include/flux/op/cartesian_power_map.hpp
+++ b/include/flux/op/cartesian_power_map.hpp
@@ -55,8 +55,10 @@ struct cartesian_power_map_fn
 
 } // namespace detail
 
-template <std::size_t PowN>
-FLUX_EXPORT inline constexpr auto cartesian_power_map = detail::cartesian_power_map_fn<PowN>{};
+FLUX_EXPORT
+template <distance_t N>
+    requires (N >= 0)
+inline constexpr auto cartesian_power_map = detail::cartesian_power_map_fn<N>{};
 
 } // namespace flux
 
diff --git a/include/flux/op/cartesian_product.hpp b/include/flux/op/cartesian_product.hpp
index 360ba25e..5a825aca 100644
--- a/include/flux/op/cartesian_product.hpp
+++ b/include/flux/op/cartesian_product.hpp
@@ -26,6 +26,10 @@ struct cartesian_product_adaptor
     FLUX_NO_UNIQUE_ADDRESS std::tuple<Bases...> bases_;
 
 public:
+    constexpr explicit cartesian_product_adaptor(decays_to<Bases> auto&&... bases)
+        : bases_(FLUX_FWD(bases)...)
+    {}
+    
     using flux_sequence_traits = cartesian_traits_base<
         sizeof...(Bases),
         cartesian_kind::product,
@@ -33,12 +37,6 @@ struct cartesian_product_adaptor
         Bases...
     >;
     friend flux_sequence_traits::impl;
-
-    constexpr explicit cartesian_product_adaptor(decays_to<Bases> auto&&... bases)
-        : bases_(FLUX_FWD(bases)...)
-    {}
-
-
 };
 
 struct cartesian_product_fn {