diff --git a/gtsam/slam/RegularHessianFactor.h b/gtsam/slam/RegularHessianFactor.h
index f3f90dc2d..8c3df87cf 100644
--- a/gtsam/slam/RegularHessianFactor.h
+++ b/gtsam/slam/RegularHessianFactor.h
@@ -55,6 +55,12 @@ public:
   typedef Eigen::Matrix<double, D, 1> DVector;
   mutable std::vector<DVector> y;
 
+  /** y += alpha * A'*A*x */
+  void multiplyHessianAdd(double alpha, const VectorValues& x, VectorValues& y) const{
+    throw std::runtime_error(
+          "RegularHessianFactor::forbidden use of multiplyHessianAdd without raw memory access, use HessianFactor instead");
+  }
+
   /** y += alpha * A'*A*x */
   void multiplyHessianAdd(double alpha, const double* x, double* yvalues) const {
     // Create a vector of temporary y values, corresponding to rows i