diff --git a/include/small/detail/container/associative_vector.hpp b/include/small/detail/container/associative_vector.hpp
index c77c4c7..266fb95 100644
--- a/include/small/detail/container/associative_vector.hpp
+++ b/include/small/detail/container/associative_vector.hpp
@@ -1129,7 +1129,7 @@ namespace small::detail {
                 || (std::is_same_v<K1, key_type>
                     && std::is_same_v<K2, key_type>),
             bool>
-        keys_equivalent(const K1 &lhs, const K2 &rhs) {
+        keys_equivalent(const K1 &lhs, const K2 &rhs) const {
             return !comp_(lhs, rhs) && !comp_(rhs, lhs);
         }