diff --git a/src/matrix2d.rs b/src/matrix2d.rs
index 779e128..a1aca3c 100644
--- a/src/matrix2d.rs
+++ b/src/matrix2d.rs
@@ -9,7 +9,7 @@
 
 use num::{One, Zero};
 
-#[deriving(Copy)]
+#[deriving(Clone, Copy)]
 pub struct Matrix2D<T> {
     m11: T, m12: T,
     m21: T, m22: T,