diff --git a/drake/systems/plants/test/rigid_body_tree/rigid_body_tree_inverse_dynamics_test.cc b/drake/systems/plants/test/rigid_body_tree/rigid_body_tree_inverse_dynamics_test.cc
index e345e46b95a3..e2ca078ff367 100644
--- a/drake/systems/plants/test/rigid_body_tree/rigid_body_tree_inverse_dynamics_test.cc
+++ b/drake/systems/plants/test/rigid_body_tree/rigid_body_tree_inverse_dynamics_test.cc
@@ -26,7 +26,7 @@ class RigidBodyTreeInverseDynamicsTest : public ::testing::Test {
   virtual void SetUp() {
     trees_.clear();
 
-    std::string kAtlasUrdf =
+    const std::string kAtlasUrdf =
         drake::GetDrakePath() + "/examples/Atlas/urdf/atlas_convex_hull.urdf";
 
     tree_rpy_.reset(new RigidBodyTree());