diff --git a/gtsam_unstable/nonlinear/Expression-inl.h b/gtsam_unstable/nonlinear/Expression-inl.h
index 43d3071ce..9b1ad8fd3 100644
--- a/gtsam_unstable/nonlinear/Expression-inl.h
+++ b/gtsam_unstable/nonlinear/Expression-inl.h
@@ -48,7 +48,6 @@ namespace gtsam {
 template<typename T>
 class Expression;
 
-//typedef std::map<Key, Eigen::Block<Matrix> > JacobianMap;
 typedef std::vector<std::pair<Key, Eigen::Block<Matrix> > > JacobianMap;
 
 //-----------------------------------------------------------------------------