diff --git a/unittest/python/test_std_vector.py b/unittest/python/test_std_vector.py
index ddc900f874f3a6a57db86bf6061a260d8b72b335..13c0edc8e6cd680f1c6d3220dc456261e4ad9042 100644
--- a/unittest/python/test_std_vector.py
+++ b/unittest/python/test_std_vector.py
@@ -8,7 +8,7 @@ np.random.seed(0)
 
 l1 = [np.random.randn(3), np.random.randn(2)]
 l2 = eigenpy.StdVec_VectorXd(l1)
-l3 = [np.random.randn(2, 2), np.random.randn(1, 2), np.random.randn(2, 6)]
+l3 = [np.random.randn(2, 2), np.random.randn(3, 1), np.random.randn(4, 2)]
 
 
 def checkAllValues(li1, li2):
@@ -33,11 +33,31 @@ print()
 l4 = [np.random.randn(3, 3) for _ in range(4)]
 assert "StdVec_Mat3d" in printVectorOf3x3.__doc__
 printVectorOf3x3(l4)
+print()
 
 l4_copy = copyStdVector(l4)
 assert isinstance(l4_copy, eigenpy.StdVec_MatrixXd)
-print(l4_copy)
 
 l4_copy2 = vector.copyStdVec_3x3(l4)
 assert isinstance(l4_copy2, vector.StdVec_Mat3d)
-print(l4_copy2)
+
+
+def checkZero(l):
+    for x in l:
+        assert np.allclose(x, 0.), "x = {}".format(x)
+
+
+print("l1:")
+vector.setZero(l1)
+print(l1)
+checkZero(l1)
+
+print("l2:")
+l2_py = l2.tolist()
+vector.setZero(l2_py)
+print(l2_py)
+checkZero(l2_py)
+
+print("l3:")
+vector.setZero(l3)
+checkZero(l3)
diff --git a/unittest/vector.cpp b/unittest/vector.cpp
index 6941b3843a1b201459e4ef577b6b4f42b94a3bbf..97201c682509081cbaf298a45c538cfad95c740a 100644
--- a/unittest/vector.cpp
+++ b/unittest/vector.cpp
@@ -18,10 +18,19 @@ std::vector<MatType> copy(const std::vector<MatType> &Ms) {
   return out;
 }
 
+template<typename MatType>
+void setZero(std::vector<MatType> Ms) {
+  for (std::size_t i = 0; i < Ms.size(); i++) {
+    Ms[i].setZero();
+  }
+}
+
+
 BOOST_PYTHON_MODULE(vector) {
   namespace bp = boost::python;
+  using namespace eigenpy;
 
-  eigenpy::enableEigenPy();
+  enableEigenPy();
 
   bp::def("printVectorOfMatrix", printVectorOfMatrix<Eigen::VectorXd>);
   bp::def("printVectorOfMatrix", printVectorOfMatrix<Eigen::MatrixXd>);
@@ -29,8 +38,12 @@ BOOST_PYTHON_MODULE(vector) {
   bp::def("copyStdVector", copy<Eigen::MatrixXd>);
   bp::def("copyStdVector", copy<Eigen::VectorXd>);
 
-  eigenpy::StdVectorPythonVisitor<std::vector<Eigen::Matrix3d>>::expose(
+  StdVectorPythonVisitor<std::vector<Eigen::Matrix3d>>::expose(
       "StdVec_Mat3d", "3D matrices.");
   bp::def("printVectorOf3x3", printVectorOfMatrix<Eigen::Matrix3d>);
   bp::def("copyStdVec_3x3", copy<Eigen::Matrix3d>, bp::args("mats"));
+
+  typedef Eigen::Ref<Eigen::MatrixXd> MatRef;
+  StdVectorPythonVisitor<std::vector<MatRef>, true>::expose("StdVec_MatRef");
+  bp::def("setZero", setZero<MatRef>, "Sets the coeff in [0,0] to 0.");
 }