diff --git a/gtsam/discrete/discrete.i b/gtsam/discrete/discrete.i
index 0bdebd0e1..753c3527a 100644
--- a/gtsam/discrete/discrete.i
+++ b/gtsam/discrete/discrete.i
@@ -112,6 +112,7 @@ virtual class DiscreteConditional : gtsam::DecisionTreeFactor {
                       const std::vector<double>& table);
 
   // Standard interface
+  double errorConstant() const;
   double logNormalizationConstant() const;
   double logProbability(const gtsam::DiscreteValues& values) const;
   double evaluate(const gtsam::DiscreteValues& values) const;