diff --git a/gtsam_unstable/nonlinear/ConcurrentBatchFilter.h b/gtsam_unstable/nonlinear/ConcurrentBatchFilter.h
index d1127b327..875eb7c79 100644
--- a/gtsam_unstable/nonlinear/ConcurrentBatchFilter.h
+++ b/gtsam_unstable/nonlinear/ConcurrentBatchFilter.h
@@ -45,7 +45,7 @@ public:
   };
 
   /** Default constructor */
-  ConcurrentBatchFilter(const LevenbergMarquardtParams& parameters) : parameters_(parameters) {};
+  ConcurrentBatchFilter(const LevenbergMarquardtParams& parameters = LevenbergMarquardtParams()) : parameters_(parameters) {};
 
   /** Default destructor */
   virtual ~ConcurrentBatchFilter() {};
diff --git a/gtsam_unstable/nonlinear/ConcurrentBatchSmoother.h b/gtsam_unstable/nonlinear/ConcurrentBatchSmoother.h
index 2b33c8b2d..637a3099a 100644
--- a/gtsam_unstable/nonlinear/ConcurrentBatchSmoother.h
+++ b/gtsam_unstable/nonlinear/ConcurrentBatchSmoother.h
@@ -45,7 +45,7 @@ public:
   };
 
   /** Default constructor */
-  ConcurrentBatchSmoother(const LevenbergMarquardtParams& parameters) : parameters_(parameters) {};
+  ConcurrentBatchSmoother(const LevenbergMarquardtParams& parameters = LevenbergMarquardtParams()) : parameters_(parameters) {};
 
   /** Default destructor */
   virtual ~ConcurrentBatchSmoother() {};