diff --git a/slam/planarSLAM.cpp b/slam/planarSLAM.cpp
index 45e315c09..417bbf8a4 100644
--- a/slam/planarSLAM.cpp
+++ b/slam/planarSLAM.cpp
@@ -20,6 +20,9 @@ namespace gtsam {
 
 	namespace planarSLAM {
 
+		Graph::Graph(const NonlinearFactorGraph<Config>& graph) :
+				NonlinearFactorGraph<Config>(graph) {}
+
 		void Graph::addPrior(const PoseKey& i, const Pose2& p,
 				const SharedGaussian& model) {
 			sharedFactor factor(new Prior(i, p, model));
diff --git a/slam/planarSLAM.h b/slam/planarSLAM.h
index d9b4e9d6d..3b0840717 100644
--- a/slam/planarSLAM.h
+++ b/slam/planarSLAM.h
@@ -37,6 +37,8 @@ namespace gtsam {
 
 		// Graph
 		struct Graph: public NonlinearFactorGraph<Config> {
+			Graph(){}
+			Graph(const NonlinearFactorGraph<Config>& graph);
 			void addPrior(const PoseKey& i, const Pose2& p, const SharedGaussian& model);
 			void addPoseConstraint(const PoseKey& i, const Pose2& p);
 			void addOdometry(const PoseKey& i, const PoseKey& j, const Pose2& z,