diff --git a/gtsam/inference/JunctionTree-inst.h b/gtsam/inference/JunctionTree-inst.h
index 92cd40665..f805b4859 100644
--- a/gtsam/inference/JunctionTree-inst.h
+++ b/gtsam/inference/JunctionTree-inst.h
@@ -291,9 +291,12 @@ namespace gtsam {
     boost::shared_ptr<BayesTreeType> result = boost::make_shared<BayesTreeType>();
     EliminationData<This> rootsContainer(0, roots_.size());
     EliminationPostOrderVisitor<This> visitorPost(function, result->nodes_);
-    //tbb::task_scheduler_init init(1);
-    treeTraversal::DepthFirstForest/*Parallel*/(*this, rootsContainer,
-      eliminationPreOrderVisitor<This>, visitorPost/*, 10*/);
+#ifdef ENABLE_TIMING
+    // In timing mode, use a single thread only, timing outline is not thread-safe.
+    tbb::task_scheduler_init init(1);
+#endif
+    treeTraversal::DepthFirstForestParallel(*this, rootsContainer,
+      eliminationPreOrderVisitor<This>, visitorPost, 10);
 
     // Create BayesTree from roots stored in the dummy BayesTree node.
     result->roots_.insert(result->roots_.end(), rootsContainer.bayesTreeNode->children.begin(), rootsContainer.bayesTreeNode->children.end());