diff --git a/Chaos/Hash/Hasher.hpp b/Chaos/Hash/Hasher.hpp
index 57f9944..4b30dd6 100644
--- a/Chaos/Hash/Hasher.hpp
+++ b/Chaos/Hash/Hasher.hpp
@@ -1,7 +1,9 @@
 #ifndef CHAOS_HASH_HASHER_HPP
 #define CHAOS_HASH_HASHER_HPP
 
+#include <concepts>
 #include <cstdint>
+#include <type_traits>
 
 #include "Hash.hpp"
 
@@ -12,6 +14,7 @@ template<typename T>
 concept Hasher = requires(T hasher, uint8_t * begin, uint8_t * end)
 {
     typename T::HashType;
+    requires std::unsigned_integral<std::remove_cvref_t<decltype(T::BLOCK_SIZE_BYTES)>>;
     hasher.Reset();
     hasher.Update(begin, end);
     { hasher.Finish() } -> Hash;