diff --git a/python/gtsam/preamble/slam.h b/python/gtsam/preamble/slam.h
index bb014ddc8..d4c2a8919 100644
--- a/python/gtsam/preamble/slam.h
+++ b/python/gtsam/preamble/slam.h
@@ -15,4 +15,4 @@ PYBIND11_MAKE_OPAQUE(
     std::vector<boost::shared_ptr<gtsam::BetweenFactor<gtsam::Pose3> > >);
 PYBIND11_MAKE_OPAQUE(
     std::vector<boost::shared_ptr<gtsam::BetweenFactor<gtsam::Pose2> > >);
-PYBIND11_MAKE_OPAQUE(std::vector<gtsam::Rot3>);
+PYBIND11_MAKE_OPAQUE(std::vector<gtsam::Rot3, Eigen::aligned_allocator<gtsam::Rot3> >);