diff --git a/rtchallenge/src/matrices.rs b/rtchallenge/src/matrices.rs
index cb67bbc..677f3b1 100644
--- a/rtchallenge/src/matrices.rs
+++ b/rtchallenge/src/matrices.rs
@@ -107,6 +107,8 @@ impl Matrix4x4 {
     ///     [0., 0., 0., 1.],
     /// );
     /// assert_eq!(m.transpose(), m_t);
+    ///
+    /// assert_eq!(Matrix4x4::identity(), Matrix4x4::identity().transpose());
     pub fn transpose(&self) -> Matrix4x4 {
         let m = self.m;
         Matrix4x4 {