diff --git a/libs/geom/include/psemek/geom/math.hpp b/libs/geom/include/psemek/geom/math.hpp
index ea820d1c..6894d080 100644
--- a/libs/geom/include/psemek/geom/math.hpp
+++ b/libs/geom/include/psemek/geom/math.hpp
@@ -25,6 +25,12 @@ namespace psemek::geom
 		return x * x;
 	}
 
+	template <typename T>
+	auto frac(T const & x)
+	{
+		return x - std::floor(x);
+	}
+
 	template <typename T>
 	T deg(T x)
 	{