diff --git a/gtsam/nonlinear/EasyFactorGraph.cpp b/gtsam/nonlinear/EasyFactorGraph.cpp
index 4f3765dec..28e344efe 100644
--- a/gtsam/nonlinear/EasyFactorGraph.cpp
+++ b/gtsam/nonlinear/EasyFactorGraph.cpp
@@ -33,14 +33,14 @@ namespace gtsam {
 		return LevenbergMarquardtOptimizer((*this), initialEstimate, p);
 	}
 
-	const Values& EasyFactorGraph::optimize(const Values& initialEstimate,
+	Values EasyFactorGraph::optimize(const Values& initialEstimate,
 			size_t verbosity) const {
 		LevenbergMarquardtParams p;
 		p.verbosity = (NonlinearOptimizerParams::Verbosity) verbosity;
 		return optimizer(initialEstimate, p).optimizeSafely();
 	}
 
-	const Values& EasyFactorGraph::optimizeSPCG(const Values& initialEstimate,
+	Values EasyFactorGraph::optimizeSPCG(const Values& initialEstimate,
 			size_t verbosity) const {
 		LevenbergMarquardtParams p;
 		p.verbosity = (NonlinearOptimizerParams::Verbosity) verbosity;
diff --git a/gtsam/nonlinear/EasyFactorGraph.h b/gtsam/nonlinear/EasyFactorGraph.h
index 131e6a06a..2629cb409 100644
--- a/gtsam/nonlinear/EasyFactorGraph.h
+++ b/gtsam/nonlinear/EasyFactorGraph.h
@@ -49,14 +49,14 @@ namespace gtsam {
 		 *  @param initialEstimate initial estimate of all variables in the graph
 		 *  @param verbosity unsigned specifying verbosity level
 		 */
-		const Values& optimize(const Values& initialEstimate, size_t verbosity = 0) const;
+		Values optimize(const Values& initialEstimate, size_t verbosity = 0) const;
 
 		/**
 		 *  Safely optimize using subgraph preconditioning
 		 *  @param initialEstimate initial estimate of all variables in the graph
 		 *  @param verbosity unsigned specifying verbosity level
 		 */
-		const Values& optimizeSPCG(const Values& initialEstimate, size_t verbosity = 0) const;
+		Values optimizeSPCG(const Values& initialEstimate, size_t verbosity = 0) const;
 
 		/**
 		 *  Return a Marginals object, so you can query marginals