diff --git a/libs/geom/include/psemek/geom/distance.hpp b/libs/geom/include/psemek/geom/distance.hpp
index d283aa21..eb33f94e 100644
--- a/libs/geom/include/psemek/geom/distance.hpp
+++ b/libs/geom/include/psemek/geom/distance.hpp
@@ -9,6 +9,14 @@
 namespace psemek::geom
 {
 
+	template <typename T>
+	T distance(T const & x, interval<T> const & i)
+	{
+		if (i.min <= x && x <= i.max)
+			return T{0};
+		return std::min(std::abs(x - i.min), std::abs(x - i.max));
+	}
+
 	template <typename T, std::size_t N>
 	T distance(point<T, N> const & p, box<T, N> const & b)
 	{