diff --git a/gtsam/geometry/Rot3.h b/gtsam/geometry/Rot3.h
index 9c1fb9a22..769596dd0 100644
--- a/gtsam/geometry/Rot3.h
+++ b/gtsam/geometry/Rot3.h
@@ -27,7 +27,7 @@
 
 namespace gtsam {
 
-  /* 3D Rotation */
+  /* 3D Rotations in GTSAM are represented as rotation matrices */
   class Rot3: Testable<Rot3>, public Lie<Rot3> {
   public:
 	  static const size_t dimension = 3;