diff --git a/libs/geom/include/psemek/geom/math.hpp b/libs/geom/include/psemek/geom/math.hpp
index 5be880fe..1ef70b72 100644
--- a/libs/geom/include/psemek/geom/math.hpp
+++ b/libs/geom/include/psemek/geom/math.hpp
@@ -8,6 +8,17 @@
 namespace psemek::geom
 {
 
+	template <typename T>
+	T sign(T const & x)
+	{
+		if (x > 0)
+			return 1;
+		else if (x < 0)
+			return -1;
+		else
+			return 0;
+	}
+
 	template <typename T>
 	auto sqr(T const & x)
 	{