diff --git a/gtsam/linear/Sampler.cpp b/gtsam/linear/Sampler.cpp
index 4957dfa14..20d4c955b 100644
--- a/gtsam/linear/Sampler.cpp
+++ b/gtsam/linear/Sampler.cpp
@@ -22,14 +22,18 @@ namespace gtsam {
 /* ************************************************************************* */
 Sampler::Sampler(const noiseModel::Diagonal::shared_ptr& model,
                  uint_fast64_t seed)
-    : model_(model), generator_(seed) {}
+    : model_(model), generator_(seed) {
+  if (!model) {
+    throw std::invalid_argument("Sampler::Sampler needs a non-null model.");
+  }
+}
 
 /* ************************************************************************* */
 Sampler::Sampler(const Vector& sigmas, uint_fast64_t seed)
     : model_(noiseModel::Diagonal::Sigmas(sigmas, true)), generator_(seed) {}
 
 /* ************************************************************************* */
-Vector Sampler::sampleDiagonal(const Vector& sigmas) const {
+Vector Sampler::sampleDiagonal(const Vector& sigmas, std::mt19937_64* rng) {
   size_t d = sigmas.size();
   Vector result(d);
   for (size_t i = 0; i < d; i++) {
@@ -39,14 +43,18 @@ Vector Sampler::sampleDiagonal(const Vector& sigmas) const {
     if (sigma == 0.0) {
       result(i) = 0.0;
     } else {
-      typedef std::normal_distribution<double> Normal;
-      Normal dist(0.0, sigma);
-      result(i) = dist(generator_);
+      std::normal_distribution<double> dist(0.0, sigma);
+      result(i) = dist(*rng);
     }
   }
   return result;
 }
 
+/* ************************************************************************* */
+Vector Sampler::sampleDiagonal(const Vector& sigmas) const {
+  return sampleDiagonal(sigmas, &generator_);
+}
+
 /* ************************************************************************* */
 Vector Sampler::sample() const {
   assert(model_.get());
diff --git a/gtsam/linear/Sampler.h b/gtsam/linear/Sampler.h
index bb5098f34..5be8b445d 100644
--- a/gtsam/linear/Sampler.h
+++ b/gtsam/linear/Sampler.h
@@ -63,15 +63,9 @@ class GTSAM_EXPORT Sampler {
   /// @name access functions
   /// @{
 
-  size_t dim() const {
-    assert(model_.get());
-    return model_->dim();
-  }
+  size_t dim() const { return model_->dim(); }
 
-  Vector sigmas() const {
-    assert(model_.get());
-    return model_->sigmas();
-  }
+  Vector sigmas() const { return model_->sigmas(); }
 
   const noiseModel::Diagonal::shared_ptr& model() const { return model_; }
 
@@ -82,6 +76,8 @@ class GTSAM_EXPORT Sampler {
   /// sample from distribution
   Vector sample() const;
 
+  /// sample with given random number generator
+  static Vector sampleDiagonal(const Vector& sigmas, std::mt19937_64* rng);
   /// @}
 
  protected: