diff --git a/gtsam_unstable/slam/TransformBtwRobotsUnaryFactorEM.h b/gtsam_unstable/slam/TransformBtwRobotsUnaryFactorEM.h
index d41d895a6..c4294fc2d 100644
--- a/gtsam_unstable/slam/TransformBtwRobotsUnaryFactorEM.h
+++ b/gtsam_unstable/slam/TransformBtwRobotsUnaryFactorEM.h
@@ -21,9 +21,12 @@
 #include <gtsam/base/Testable.h>
 #include <gtsam/base/Lie.h>
 #include <gtsam/nonlinear/NonlinearFactor.h>
+#include <gtsam/nonlinear/NonlinearFactorGraph.h>
+#include <gtsam/nonlinear/Marginals.h>
 #include <gtsam/linear/GaussianFactor.h>
 #include <gtsam/slam/BetweenFactor.h>
 
+
 namespace gtsam {
 
   /**