diff --git a/gtsam_unstable/nonlinear/Expression-inl.h b/gtsam_unstable/nonlinear/Expression-inl.h
index 45a932351..87c07f976 100644
--- a/gtsam_unstable/nonlinear/Expression-inl.h
+++ b/gtsam_unstable/nonlinear/Expression-inl.h
@@ -647,45 +647,23 @@ public:
   }
 
   /// Trace structure for reverse AD
-  struct Trace: public JacobianTrace<T> {
-    typename JacobianTrace<A1>::Pointer trace1;
-    typename JacobianTrace<A2>::Pointer trace2;
-    typename JacobianTrace<A3>::Pointer trace3;
-    JacobianTA1 dTdA1;
-    JacobianTA2 dTdA2;
-    JacobianTA3 dTdA3;
-
-    /// Start the reverse AD process
-    virtual void startReverseAD(JacobianMap& jacobians) const {
-      Select<T::dimension, A1>::reverseAD(trace1, dTdA1, jacobians);
-      Select<T::dimension, A2>::reverseAD(trace2, dTdA2, jacobians);
-      Select<T::dimension, A3>::reverseAD(trace3, dTdA3, jacobians);
-    }
-    /// Given df/dT, multiply in dT/dA and continue reverse AD process
-    virtual void reverseAD(const Matrix& dFdT, JacobianMap& jacobians) const {
-      trace1.reverseAD(dFdT * dTdA1, jacobians);
-      trace2.reverseAD(dFdT * dTdA2, jacobians);
-      trace3.reverseAD(dFdT * dTdA3, jacobians);
-    }
-    /// Version specialized to 2-dimensional output
-    typedef Eigen::Matrix<double, 2, T::dimension> Jacobian2T;
-    virtual void reverseAD2(const Jacobian2T& dFdT,
-        JacobianMap& jacobians) const {
-      trace1.reverseAD2(dFdT * dTdA1, jacobians);
-      trace2.reverseAD2(dFdT * dTdA2, jacobians);
-      trace3.reverseAD2(dFdT * dTdA3, jacobians);
-    }
-  };
+  typedef boost::mpl::vector<A1, A2, A3> Arguments;
+  typedef typename GenerateTrace<T, Arguments>::type Trace;
 
   /// Construct an execution trace for reverse AD
   virtual T traceExecution(const Values& values,
       typename JacobianTrace<T>::Pointer& p) const {
     Trace* trace = new Trace();
     p.setFunction(trace);
-    A1 a1 = this->expressionA1_->traceExecution(values, trace->trace1);
-    A2 a2 = this->expressionA2_->traceExecution(values, trace->trace2);
-    A3 a3 = this->expressionA3_->traceExecution(values, trace->trace3);
-    return function_(a1, a2, a3, trace->dTdA1, trace->dTdA2, trace->dTdA3);
+    A1 a1 = this->expressionA1_->traceExecution(values,
+        static_cast<SingleTrace<T, A1>*>(trace)->trace);
+    A2 a2 = this->expressionA2_->traceExecution(values,
+        static_cast<SingleTrace<T, A2>*>(trace)->trace);
+    A3 a3 = this->expressionA3_->traceExecution(values,
+        static_cast<SingleTrace<T, A3>*>(trace)->trace);
+    return function_(a1, a2, a3, static_cast<SingleTrace<T, A1>*>(trace)->dTdA,
+        static_cast<SingleTrace<T, A2>*>(trace)->dTdA,
+        static_cast<SingleTrace<T, A3>*>(trace)->dTdA);
   }
 
 };