diff --git a/headers/Containers/Hashing.hpp b/headers/Containers/Hashing.hpp
index 7af88cf..4f64711 100644
--- a/headers/Containers/Hashing.hpp
+++ b/headers/Containers/Hashing.hpp
@@ -15,6 +15,7 @@
 namespace Tourmaline::Containers {
 template <typename T>
 concept Hashable = requires(T x) {
+  std::equality_comparable<T>;
   { std::hash<T>{}(x) } -> std::convertible_to<std::size_t>;
 };
 } // namespace Tourmaline::Containers