diff --git a/gtsam/discrete/DiscreteMarginals.h b/gtsam/discrete/DiscreteMarginals.h
index 27352a211..a2207a10b 100644
--- a/gtsam/discrete/DiscreteMarginals.h
+++ b/gtsam/discrete/DiscreteMarginals.h
@@ -37,6 +37,8 @@ class GTSAM_EXPORT DiscreteMarginals {
 
   public:
 
+  DiscreteMarginals() {}
+
   /** Construct a marginals class.
    * @param graph The factor graph defining the full joint density on all variables.
    */