diff --git a/libs/util/include/psemek/util/array.hpp b/libs/util/include/psemek/util/array.hpp
index 8a6d0211..9e9eb65d 100644
--- a/libs/util/include/psemek/util/array.hpp
+++ b/libs/util/include/psemek/util/array.hpp
@@ -45,13 +45,13 @@ namespace psemek::util
 			return dims_[0];
 		}
 
-		std::size_t height()
+		std::size_t height() const
 		{
 			static_assert(N >= 2);
 			return dims_[1];
 		}
 
-		std::size_t depth()
+		std::size_t depth() const
 		{
 			static_assert(N >= 3);
 			return dims_[2];
@@ -131,7 +131,7 @@ namespace psemek::util
 		}
 
 		template <std::size_t N>
-		bool next(std::array<std::size_t, N> const & i, std::array<std::size_t, N> const & dims)
+		bool next(std::array<std::size_t, N> & i, std::array<std::size_t, N> const & dims)
 		{
 			for (std::size_t d = 0; d < N; ++d)
 			{