diff --git a/gtsam_unstable/nonlinear/AdaptAutoDiff.h b/gtsam_unstable/nonlinear/AdaptAutoDiff.h
index 96978d9cf..70ba285c1 100644
--- a/gtsam_unstable/nonlinear/AdaptAutoDiff.h
+++ b/gtsam_unstable/nonlinear/AdaptAutoDiff.h
@@ -50,11 +50,8 @@ class AdaptAutoDiff {
 
 public:
 
-  typedef Eigen::Matrix<double, N, M1> JacobianTA1;
-  typedef Eigen::Matrix<double, N, M2> JacobianTA2;
-
-  T operator()(const A1& a1, const A2& a2, boost::optional<JacobianTA1&> H1 =
-      boost::none, boost::optional<JacobianTA2&> H2 = boost::none) {
+  T operator()(const A1& a1, const A2& a2, FixedRef<N, M1> H1 = boost::none,
+      FixedRef<N, M2> H2 = boost::none) {
 
     using ceres::internal::AutoDiff;