diff --git a/gtsam/linear/JacobianFactor.h b/gtsam/linear/JacobianFactor.h
index f5a2e9c62..55bcedf1d 100644
--- a/gtsam/linear/JacobianFactor.h
+++ b/gtsam/linear/JacobianFactor.h
@@ -301,12 +301,14 @@ namespace gtsam {
      */
     boost::shared_ptr<GaussianConditional> splitConditional(size_t nrFrontals);
 
-  private:
+  protected:
 
     /// Internal function to fill blocks and set dimensions
     template<typename TERMS>
     void fillTerms(const TERMS& terms, const Vector& b, const SharedDiagonal& noiseModel);
     
+  private:
+
     /** Serialization function */
     friend class boost::serialization::access;
     template<class ARCHIVE>