diff --git a/include/flux/core/concepts.hpp b/include/flux/core/concepts.hpp
index 5235c70e..faa1659c 100644
--- a/include/flux/core/concepts.hpp
+++ b/include/flux/core/concepts.hpp
@@ -380,23 +380,6 @@ template <typename T>
 struct sequence_traits<T> : T::flux_sequence_traits {};
 
 
-namespace detail {
-
-template <typename Func, typename E, distance_t N>
-struct repeated_invocable_helper {
-    template <std::size_t I>
-    using repeater = E;
-
-    static inline constexpr bool value = []<std::size_t... Is> (std::index_sequence<Is...>) consteval {
-        return std::regular_invocable<Func, repeater<Is>...>;
-    }(std::make_index_sequence<N>{});
-};
-
-template <typename Func, typename E, distance_t N>
-concept repeated_invocable = repeated_invocable_helper<Func, E, N>::value;
-
-} // namespace detail
-
 } // namespace flux
 
 #endif // FLUX_CORE_CONCEPTS_HPP_INCLUDED
diff --git a/include/flux/op/cartesian_power_map.hpp b/include/flux/op/cartesian_power_map.hpp
index 45c8a536..4e288faa 100644
--- a/include/flux/op/cartesian_power_map.hpp
+++ b/include/flux/op/cartesian_power_map.hpp
@@ -7,6 +7,7 @@
 #define FLUX_OP_CARTESIAN_POWER_MAP_HPP_INCLUDED
 
 #include <flux/op/cartesian_base.hpp>
+#include <flux/op/requirements.hpp>
 
 namespace flux {
 
diff --git a/include/flux/op/requirements.hpp b/include/flux/op/requirements.hpp
index 21bcf57e..0d059ddc 100644
--- a/include/flux/op/requirements.hpp
+++ b/include/flux/op/requirements.hpp
@@ -25,6 +25,23 @@ concept foldable_ =
 
 } // namespace detail
 
+namespace detail {
+
+template <typename Func, typename E, distance_t N>
+struct repeated_invocable_helper {
+    template <std::size_t I>
+    using repeater = E;
+
+    static inline constexpr bool value = []<std::size_t... Is> (std::index_sequence<Is...>) consteval {
+        return std::regular_invocable<Func, repeater<Is>...>;
+    }(std::make_index_sequence<N>{});
+};
+
+template <typename Func, typename E, distance_t N>
+concept repeated_invocable = repeated_invocable_helper<Func, E, N>::value;
+
+} // namespace detail
+
 FLUX_EXPORT
 template <typename Seq, typename Func, typename Init>
 concept foldable =