diff --git a/gtsam/linear/IterativeSolver.cpp b/gtsam/linear/IterativeSolver.cpp
index c5007206d..5adb1916a 100644
--- a/gtsam/linear/IterativeSolver.cpp
+++ b/gtsam/linear/IterativeSolver.cpp
@@ -84,8 +84,7 @@ string IterativeOptimizationParameters::verbosityTranslator(
 
 /*****************************************************************************/
 VectorValues IterativeSolver::optimize(const GaussianFactorGraph &gfg,
-    boost::optional<const KeyInfo&> keyInfo,
-    boost::optional<const std::map<Key, Vector>&> lambda) {
+    const KeyInfo* keyInfo, const std::map<Key, Vector>* lambda) {
   return optimize(gfg, keyInfo ? *keyInfo : KeyInfo(gfg),
       lambda ? *lambda : std::map<Key, Vector>());
 }
diff --git a/gtsam/linear/IterativeSolver.h b/gtsam/linear/IterativeSolver.h
index 758d2aec9..cd3f41659 100644
--- a/gtsam/linear/IterativeSolver.h
+++ b/gtsam/linear/IterativeSolver.h
@@ -93,8 +93,8 @@ public:
 
   /* interface to the nonlinear optimizer, without metadata, damping and initial estimate */
   GTSAM_EXPORT VectorValues optimize(const GaussianFactorGraph &gfg,
-      boost::optional<const KeyInfo&> = boost::none,
-      boost::optional<const std::map<Key, Vector>&> lambda = boost::none);
+      const KeyInfo* = nullptr,
+      const std::map<Key, Vector>* lambda = nullptr);
 
   /* interface to the nonlinear optimizer, without initial estimate */
   GTSAM_EXPORT VectorValues optimize(const GaussianFactorGraph &gfg, const KeyInfo &keyInfo,