diff --git a/libs/geom/include/psemek/geom/interval.hpp b/libs/geom/include/psemek/geom/interval.hpp
index 6d805f75..bf63d079 100644
--- a/libs/geom/include/psemek/geom/interval.hpp
+++ b/libs/geom/include/psemek/geom/interval.hpp
@@ -294,4 +294,11 @@ namespace psemek::geom
 		return std::isfinite(i.min) && std::isfinite(i.max);
 	}
 
+	template <typename T>
+	requires(std::is_integral_v<T>)
+	interval<T> closed(interval<T> const & i)
+	{
+		return {i.min, i.max + T(1)};
+	}
+
 }