diff --git a/libs/pcg/include/psemek/pcg/lazy_perlin.hpp b/libs/pcg/include/psemek/pcg/lazy_perlin.hpp
index fbe6d4ff..39767702 100644
--- a/libs/pcg/include/psemek/pcg/lazy_perlin.hpp
+++ b/libs/pcg/include/psemek/pcg/lazy_perlin.hpp
@@ -7,6 +7,7 @@
 #include <psemek/geom/box.hpp>
 
 #include <unordered_map>
+#include <optional>
 
 namespace psemek::pcg
 {
@@ -15,7 +16,7 @@ namespace psemek::pcg
 	{
 
 		template <typename T, std::size_t N, typename F, typename G>
-		T perlin_impl(geom::vector<T, N> p, int grid_size, F && grid_at, G && bound)
+		T perlin_impl(geom::point<T, N> p, int grid_size, F && grid_at, G && bound)
 		{
 			geom::vector<int, N> ip;
 			for (std::size_t i = 0; i < N; ++i)
@@ -24,7 +25,7 @@ namespace psemek::pcg
 			}
 			ip = bound(ip);
 
-			geom::vector<T, N> t = (p - geom::cast<T>(ip) * T(grid_size)) / T(grid_size);
+			geom::vector<T, N> t = (p - p.zero() - geom::cast<T>(ip) * T(grid_size)) / T(grid_size);
 
 			T values[1 << N];
 
@@ -73,7 +74,7 @@ namespace psemek::pcg
 			, subgrid_(std::move(subgrid))
 		{}
 
-		T operator()(geom::vector<T, N> p) const;
+		T operator()(geom::point<T, N> p) const;
 
 	private:
 		int grid_size_;
@@ -94,7 +95,7 @@ namespace psemek::pcg
 			, gen_(std::move(generator))
 		{}
 
-		T operator()(geom::vector<T, N> p) const;
+		T operator()(geom::point<T, N> p) const;
 
 		auto subview(geom::box<T, N> const & box) const;
 
@@ -136,7 +137,7 @@ namespace psemek::pcg
 			grid_.resize(dims);
 		}
 
-		T operator()(geom::vector<T, N> p) const;
+		T operator()(geom::point<T, N> p) const;
 
 	private:
 		int const grid_size_;
@@ -158,7 +159,7 @@ namespace psemek::pcg
 	};
 
 	template <typename T, std::size_t N>
-	T lazy_perlin_view<T, N>::operator()(geom::vector<T, N> p) const
+	T lazy_perlin_view<T, N>::operator()(geom::point<T, N> p) const
 	{
 		return detail::perlin_impl(p, grid_size_, [this](auto const & c){
 			return subgrid_(c - origin_);
@@ -173,7 +174,7 @@ namespace psemek::pcg
 	}
 
 	template <typename T, std::size_t N>
-	T lazy_perlin<T, N>::operator()(geom::vector<T, N> p) const
+	T lazy_perlin<T, N>::operator()(geom::point<T, N> p) const
 	{
 		return detail::perlin_impl(p, grid_size_, [this](auto const & c){ return grid_at(c); }, [](auto const & p){ return p; });
 	}
@@ -203,7 +204,7 @@ namespace psemek::pcg
 	}
 
 	template <typename T, std::size_t N>
-	T bounded_lazy_perlin<T, N>::operator()(geom::vector<T, N> p) const
+	T bounded_lazy_perlin<T, N>::operator()(geom::point<T, N> p) const
 	{
 		return detail::perlin_impl(p, grid_size_, [this](auto const & c){ return grid_at(c); }, [this](auto p){
 			for (std::size_t i = 0; i < N; ++i)