diff --git a/gtsam/discrete/discrete.i b/gtsam/discrete/discrete.i
index 2f6687d44..54d00f82a 100644
--- a/gtsam/discrete/discrete.i
+++ b/gtsam/discrete/discrete.i
@@ -139,12 +139,12 @@ virtual class DiscreteConditional : gtsam::DecisionTreeFactor {
       const gtsam::DiscreteValues& frontalValues) const;
   gtsam::DecisionTreeFactor* likelihood(size_t value) const;
   size_t sample(const gtsam::DiscreteValues& parentsValues,
-                std::mt19937_64 @rng = &kRandomNumberGenerator) const;
+                std::mt19937_64 @rng = nullptr) const;
   size_t sample(size_t value,
-                std::mt19937_64 @rng = &kRandomNumberGenerator) const;
-  size_t sample(std::mt19937_64 @rng = &kRandomNumberGenerator) const;
+                std::mt19937_64 @rng = nullptr) const;
+  size_t sample(std::mt19937_64 @rng = nullptr) const;
   void sampleInPlace(gtsam::DiscreteValues @parentsValues,
-                     std::mt19937_64 @rng = &kRandomNumberGenerator) const;
+                     std::mt19937_64 @rng = nullptr) const;
   size_t argmax(const gtsam::DiscreteValues& parentsValues) const;
 
   // Markdown and HTML
@@ -237,10 +237,10 @@ class DiscreteBayesNet {
   double operator()(const gtsam::DiscreteValues& values) const;
 
   gtsam::DiscreteValues sample(std::mt19937_64
-                               @rng = &kRandomNumberGenerator) const;
+                               @rng = nullptr) const;
   gtsam::DiscreteValues sample(gtsam::DiscreteValues given,
                                std::mt19937_64
-                               @rng = &kRandomNumberGenerator) const;
+                               @rng = nullptr) const;
 
   string dot(
       const gtsam::KeyFormatter& keyFormatter = gtsam::DefaultKeyFormatter,