diff --git a/libs/geom/include/psemek/geom/hermite.hpp b/libs/geom/include/psemek/geom/hermite.hpp
index c4de2694..5a928e71 100644
--- a/libs/geom/include/psemek/geom/hermite.hpp
+++ b/libs/geom/include/psemek/geom/hermite.hpp
@@ -6,7 +6,7 @@ namespace psemek::geom
 	template <typename T>
 	struct cubic_hermite
 	{
-		T a[3];
+		T a[4];
 
 		cubic_hermite() = default;
 		cubic_hermite(T p0, T m0, T p1, T m1)