diff --git a/extent.hpp b/extent.hpp
index ad28157c..016545d8 100644
--- a/extent.hpp
+++ b/extent.hpp
@@ -87,6 +87,11 @@ namespace util {
     template <typename T> using extent2 = extent<2,T>;
     template <typename T> using extent3 = extent<3,T>;
 
+    template <size_t S> using extentu = extent<S,size_t>;
+    template <size_t S> using extenti = extent<S,intmax_t>;
+    template <size_t S> using extentf = extent<S,float>;
+    template <size_t S> using extentd = extent<S,double>;
+
     typedef extent2<intmax_t> extent2i;
     typedef extent2<size_t> extent2u;
     typedef extent2<float> extent2f;