diff --git a/include/aikido/control/BarrettHandKinematicSimulationPositionCommandExecutor.hpp b/include/aikido/control/BarrettHandKinematicSimulationPositionCommandExecutor.hpp
index c83c477e92..08f93f52a3 100644
--- a/include/aikido/control/BarrettHandKinematicSimulationPositionCommandExecutor.hpp
+++ b/include/aikido/control/BarrettHandKinematicSimulationPositionCommandExecutor.hpp
@@ -47,7 +47,9 @@ class BarrettHandKinematicSimulationPositionCommandExecutor
   /// \return Future which becomes available when the execution completes.
   std::future<void> execute(const Eigen::VectorXd& goalPositions) override;
 
-  // Documentation inherited.
+  /// If multiple threads are accessing this function or the skeleton associated
+  /// with this executor, it is necessary to lock the skeleton before
+  /// calling this method.
   void step() override;
 
   /// Resets CollisionGroup to check collision with fingers.
diff --git a/include/aikido/control/KinematicSimulationTrajectoryExecutor.hpp b/include/aikido/control/KinematicSimulationTrajectoryExecutor.hpp
index 945129e6d2..61e01996a9 100644
--- a/include/aikido/control/KinematicSimulationTrajectoryExecutor.hpp
+++ b/include/aikido/control/KinematicSimulationTrajectoryExecutor.hpp
@@ -35,7 +35,9 @@ class KinematicSimulationTrajectoryExecutor : public TrajectoryExecutor
   std::future<void> execute(
     trajectory::TrajectoryPtr traj) override;
 
-  // Documentation inherited.
+  /// If multiple threads are accessing this function or the skeleton associated
+  /// with this executor, it is necessary to lock the skeleton before
+  /// calling this method.
   void step() override;
 
 private:
diff --git a/src/control/KinematicSimulationTrajectoryExecutor.cpp b/src/control/KinematicSimulationTrajectoryExecutor.cpp
index 2a127d9098..0fd2aafe51 100644
--- a/src/control/KinematicSimulationTrajectoryExecutor.cpp
+++ b/src/control/KinematicSimulationTrajectoryExecutor.cpp
@@ -106,7 +106,7 @@ void KinematicSimulationTrajectoryExecutor::step()
   }
 
   auto timeSinceBeginning = system_clock::now() - mExecutionStartTime;
-  double t = duration_cast<seconds>(timeSinceBeginning).count();
+  auto t = duration<double>(timeSinceBeginning).count();
 
   // Can't do static here because MetaSkeletonStateSpace inherits
   // CartesianProduct which inherits virtual StateSpace
@@ -117,10 +117,7 @@ void KinematicSimulationTrajectoryExecutor::step()
 
   mTraj->evaluate(t, state);
 
-  // Lock the skeleton, set state.
-  std::unique_lock<std::mutex> skeleton_lock(mSkeleton->getMutex());
   space->setState(state);
-  skeleton_lock.unlock();
 
   // Check if trajectory has completed.
   bool const is_done = (t >= mTraj->getEndTime());
@@ -129,6 +126,7 @@ void KinematicSimulationTrajectoryExecutor::step()
     mPromise->set_value();
     mInExecution = false;
   }
+
 }
 
 }