diff --git a/linear/NoiseModel.h b/linear/NoiseModel.h
index a849251ff..d069e0861 100644
--- a/linear/NoiseModel.h
+++ b/linear/NoiseModel.h
@@ -397,5 +397,4 @@ namespace gtsam {
 
 	} // namespace noiseModel
 
-	using namespace noiseModel;
 } // namespace gtsam
diff --git a/tests/testIterative.cpp b/tests/testIterative.cpp
index c0f7e6efe..543295b6f 100644
--- a/tests/testIterative.cpp
+++ b/tests/testIterative.cpp
@@ -115,8 +115,8 @@ TEST( Iterative, conjugateGradientDescent_soft_constraint )
 	config.insert(2, Pose2(1.5,0.,0.));
 
 	Pose2Graph graph;
-	graph.addPrior(1, Pose2(0.,0.,0.), Isotropic::Sigma(3, 1e-10));
-	graph.addConstraint(1,2, Pose2(1.,0.,0.), Isotropic::Sigma(3, 1));
+	graph.addPrior(1, Pose2(0.,0.,0.), noiseModel::Isotropic::Sigma(3, 1e-10));
+	graph.addConstraint(1,2, Pose2(1.,0.,0.), noiseModel::Isotropic::Sigma(3, 1));
 
 	VectorConfig zeros;
 	zeros.insert("x1",zero(3));
@@ -141,8 +141,8 @@ TEST( Iterative, subgraphPCG )
 	theta_bar.insert(2, Pose2(1.5,0.,0.));
 
 	Pose2Graph graph;
-	graph.addPrior(1, Pose2(0.,0.,0.), Isotropic::Sigma(3, 1e-10));
-	graph.addConstraint(1,2, Pose2(1.,0.,0.), Isotropic::Sigma(3, 1));
+	graph.addPrior(1, Pose2(0.,0.,0.), noiseModel::Isotropic::Sigma(3, 1e-10));
+	graph.addConstraint(1,2, Pose2(1.,0.,0.), noiseModel::Isotropic::Sigma(3, 1));
 
 	// generate spanning tree and create ordering
 	PredecessorMap<Key> tree = graph.findMinimumSpanningTree<Key, Pose2Factor>();
diff --git a/tests/testNonlinearOptimizer.cpp b/tests/testNonlinearOptimizer.cpp
index f29d0fb6a..2c7cb73bc 100644
--- a/tests/testNonlinearOptimizer.cpp
+++ b/tests/testNonlinearOptimizer.cpp
@@ -224,8 +224,8 @@ TEST( NonlinearOptimizer, Factorization )
 	config->insert(2, Pose2(1.5,0.,0.));
 
 	boost::shared_ptr<Pose2Graph> graph(new Pose2Graph);
-	graph->addPrior(1, Pose2(0.,0.,0.), Isotropic::Sigma(3, 1e-10));
-	graph->addConstraint(1,2, Pose2(1.,0.,0.), Isotropic::Sigma(3, 1));
+	graph->addPrior(1, Pose2(0.,0.,0.), noiseModel::Isotropic::Sigma(3, 1e-10));
+	graph->addConstraint(1,2, Pose2(1.,0.,0.), noiseModel::Isotropic::Sigma(3, 1));
 
 	boost::shared_ptr<Ordering> ordering(new Ordering);
 	ordering->push_back(Pose2Config::Key(1));
@@ -250,8 +250,8 @@ TEST( NonlinearOptimizer, SubgraphSolver )
 
 	// Create a graph
 	boost::shared_ptr<Graph> graph(new Graph);
-	graph->addPrior(1, Pose2(0., 0., 0.), Isotropic::Sigma(3, 1e-10));
-	graph->addConstraint(1, 2, Pose2(1., 0., 0.), Isotropic::Sigma(3, 1));
+	graph->addPrior(1, Pose2(0., 0., 0.), noiseModel::Isotropic::Sigma(3, 1e-10));
+	graph->addConstraint(1, 2, Pose2(1., 0., 0.), noiseModel::Isotropic::Sigma(3, 1));
 
 	// Create an initial config
 	boost::shared_ptr<Config> config(new Config);