diff --git a/libs/geom/include/psemek/geom/constants.hpp b/libs/geom/include/psemek/geom/constants.hpp
index d8fe5391..b97162fc 100644
--- a/libs/geom/include/psemek/geom/constants.hpp
+++ b/libs/geom/include/psemek/geom/constants.hpp
@@ -5,4 +5,6 @@ namespace psemek::geom
 
 	constexpr long double pi = 3.141592653589793238462643383279502884l;
 
+	constexpr long double phi = 1.61803398874989484820l;
+
 }