diff --git a/geom/aabb.hpp b/geom/aabb.hpp
index cbd7fa72..08215049 100644
--- a/geom/aabb.hpp
+++ b/geom/aabb.hpp
@@ -148,6 +148,7 @@ namespace cruft::geom::sample {
     public:
         using shape_type = aabb<S,T>;
 
+        volume (shape_type&&);
         volume (shape_type const &target):
             m_target (target)
         { ; }
diff --git a/geom/ellipse.hpp b/geom/ellipse.hpp
index 3a3bae3e..8ed89cc7 100644
--- a/geom/ellipse.hpp
+++ b/geom/ellipse.hpp
@@ -152,6 +152,7 @@ namespace cruft::geom::sample {
     public:
         using shape_type = ellipse<2,T>;
 
+        volume (shape_type &&) = delete;
         volume (shape_type const &target):
             m_target (target)
         { ; }
diff --git a/geom/sample/volume.hpp b/geom/sample/volume.hpp
index 95dec1ec..5104a252 100644
--- a/geom/sample/volume.hpp
+++ b/geom/sample/volume.hpp
@@ -49,7 +49,10 @@ namespace cruft::geom::sample {
     template <typename ShapeT>
     class volume {
     public:
-        explicit volume (ShapeT const &target):
+        using shape_type = ShapeT;
+
+        explicit volume (shape_type&&) = delete;
+        explicit volume (shape_type const &target):
             m_target (target)
         { ; }
 
@@ -82,6 +85,7 @@ namespace cruft::geom::sample {
     public:
         using shape_type = extent<S,T>;
 
+        explicit volume (shape_type&&) = delete;
         explicit volume (shape_type const &target):
             m_target (target)
         { ; }