diff --git a/gtsam_unstable/nonlinear/Expression-inl.h b/gtsam_unstable/nonlinear/Expression-inl.h
index d5c5f1279..9327d0803 100644
--- a/gtsam_unstable/nonlinear/Expression-inl.h
+++ b/gtsam_unstable/nonlinear/Expression-inl.h
@@ -26,6 +26,7 @@
 
 #include <boost/foreach.hpp>
 #include <boost/tuple/tuple.hpp>
+#include <boost/bind.hpp>
 
 // template meta-programming headers
 #include <boost/mpl/vector.hpp>
@@ -48,7 +49,8 @@ namespace gtsam {
 template<typename T>
 class Expression;
 
-typedef std::map<Key, Eigen::Block<Matrix> > JacobianMap;
+typedef std::pair<Key, Eigen::Block<Matrix> > JacobianPair;
+typedef std::vector<JacobianPair> JacobianMap;
 
 //-----------------------------------------------------------------------------
 /**
@@ -78,15 +80,19 @@ struct CallRecord {
 template<int ROWS, int COLS>
 void handleLeafCase(const Eigen::Matrix<double, ROWS, COLS>& dTdA,
     JacobianMap& jacobians, Key key) {
-  JacobianMap::iterator it = jacobians.find(key);
-  it->second.block<ROWS, COLS>(0, 0) += dTdA; // block makes HUGE difference
+  JacobianMap::iterator it = std::find_if(jacobians.begin(), jacobians.end(),
+      boost::bind(&JacobianPair::first, _1) == key);
+  assert(it!=jacobians.end());
+  it->second.block < ROWS, COLS > (0, 0) += dTdA; // block makes HUGE difference
 }
 /// Handle Leaf Case for Dynamic Matrix type (slower)
 template<>
 void handleLeafCase(
     const Eigen::Matrix<double, Eigen::Dynamic, Eigen::Dynamic>& dTdA,
     JacobianMap& jacobians, Key key) {
-  JacobianMap::iterator it = jacobians.find(key);
+  JacobianMap::iterator it = std::find_if(jacobians.begin(), jacobians.end(),
+      boost::bind(&JacobianPair::first, _1) == key);
+  assert(it!=jacobians.end());
   it->second += dTdA;
 }
 
diff --git a/gtsam_unstable/nonlinear/ExpressionFactor.h b/gtsam_unstable/nonlinear/ExpressionFactor.h
index 84456c934..c9f3fae86 100644
--- a/gtsam_unstable/nonlinear/ExpressionFactor.h
+++ b/gtsam_unstable/nonlinear/ExpressionFactor.h
@@ -87,12 +87,13 @@ public:
 
       // Create and zero out blocks to be passed to expression_
       JacobianMap blocks;
+      blocks.reserve(size());
       for (DenseIndex i = 0; i < size(); i++) {
         Matrix& Hi = H->at(i);
         Hi.resize(Dim, dimensions_[i]);
         Hi.setZero(); // zero out
         Eigen::Block<Matrix> block = Hi.block(0, 0, Dim, dimensions_[i]);
-        blocks.insert(std::make_pair(keys_[i], block));
+        blocks.push_back(std::make_pair(keys_[i], block));
       }
 
       T value = expression_.value(x, blocks);
@@ -121,8 +122,9 @@ public:
 
     // Create blocks into Ab_ to be passed to expression_
     JacobianMap blocks;
+    blocks.reserve(size());
     for (DenseIndex i = 0; i < size(); i++)
-      blocks.insert(std::make_pair(keys_[i], Ab(i)));
+      blocks.push_back(std::make_pair(keys_[i], Ab(i)));
 
     // Evaluate error to get Jacobians and RHS vector b
     T value = expression_.value(x, blocks); // <<< Reverse AD happens here !
diff --git a/gtsam_unstable/nonlinear/tests/testAdaptAutoDiff.cpp b/gtsam_unstable/nonlinear/tests/testAdaptAutoDiff.cpp
index dc07c4b46..f26a1e61d 100644
--- a/gtsam_unstable/nonlinear/tests/testAdaptAutoDiff.cpp
+++ b/gtsam_unstable/nonlinear/tests/testAdaptAutoDiff.cpp
@@ -202,7 +202,7 @@ TEST(Expression, Snavely) {
 #ifdef GTSAM_USE_QUATERNIONS
   EXPECT_LONGS_EQUAL(480,expression.traceSize()); // Todo, should be zero
 #else
-  EXPECT_LONGS_EQUAL(528,expression.traceSize()); // Todo, should be zero
+  EXPECT_LONGS_EQUAL(448,expression.traceSize()); // Todo, should be zero
 #endif
   set<Key> expected = list_of(1)(2);
   EXPECT(expected == expression.keys());
diff --git a/gtsam_unstable/nonlinear/tests/testExpression.cpp b/gtsam_unstable/nonlinear/tests/testExpression.cpp
index 1997bdb53..90469d8c5 100644
--- a/gtsam_unstable/nonlinear/tests/testExpression.cpp
+++ b/gtsam_unstable/nonlinear/tests/testExpression.cpp
@@ -63,10 +63,10 @@ TEST(Expression, Leaf) {
 
   JacobianMap expected;
   Matrix H = eye(3);
-  expected.insert(make_pair(100, H.block(0, 0, 3, 3)));
+  expected.push_back(make_pair(100, H.block(0, 0, 3, 3)));
 
   JacobianMap actualMap2;
-  actualMap2.insert(make_pair(100, H.block(0, 0, 3, 3)));
+  actualMap2.push_back(make_pair(100, H.block(0, 0, 3, 3)));
   Rot3 actual2 = R.reverse(values, actualMap2);
   EXPECT(assert_equal(someR, actual2));
   EXPECT(actualMap2 == expected);