diff --git a/coord/traits.hpp b/coord/traits.hpp
index 6f332f07..a1a7b03f 100644
--- a/coord/traits.hpp
+++ b/coord/traits.hpp
@@ -70,6 +70,7 @@ namespace util {
     RESULT_T(point,vector,point)
     RESULT_T(srgba,vector,srgba)
     RESULT_T(srgba,srgba,srgba)
+    RESULT_T(vector,extent,extent)
     RESULT_T(vector,point,point)
     RESULT_T(vector,srgba,srgba)
     RESULT_T(vector,vector,vector)