diff --git a/gtsam/linear/GaussianConditional.cpp b/gtsam/linear/GaussianConditional.cpp
index 85b17373c..4597156bc 100644
--- a/gtsam/linear/GaussianConditional.cpp
+++ b/gtsam/linear/GaussianConditional.cpp
@@ -300,21 +300,11 @@ double GaussianConditional::logDeterminant() const {
           "conditionals");
     }
 
-    // Noise model to sample from.
-    noiseModel::Diagonal::shared_ptr _model;
-    if (!model_) {
-      // Initialize model_ to Unit noiseModel if not initialized.
-      // Unit noise model specifies sigmas as 1, since
-      // the noise information should already be in information matrix A.
-      // Dim should be number of rows since
-      // noise model dimension should match (Ax - b)
-      _model = noiseModel::Unit::Create(rows());
-    } else {
-      _model = model_;
-    }
     VectorValues solution = solve(parentsValues);
     Key key = firstFrontalKey();
-    const Vector& sigmas = _model->sigmas();
+    // The vector of sigma values for sampling.
+    // If no model, initialize sigmas to 1, else to model sigmas
+    const Vector& sigmas = (!model_) ? Vector::Ones(rows()) : model_->sigmas();
     solution[key] += Sampler::sampleDiagonal(sigmas, rng);
     return solution;
   }