diff --git a/matrix/Quaternion.hpp b/matrix/Quaternion.hpp
index 87bea23d2c..a17205fc12 100644
--- a/matrix/Quaternion.hpp
+++ b/matrix/Quaternion.hpp
@@ -510,7 +510,7 @@ public:
     /**
      * XXX DEPRECATED, can use assignment or ctor
      */
-    Quaternion from_dcm(Matrix<Type, 3, 3> dcm) {
+    Quaternion from_dcm(const Matrix<Type, 3, 3>& dcm) {
         return Quaternion(Dcmf(dcm));
     }