diff --git a/search/MakeTimingModel.cc b/search/MakeTimingModel.cc
index 0b75e964..9a20abea 100644
--- a/search/MakeTimingModel.cc
+++ b/search/MakeTimingModel.cc
@@ -94,7 +94,6 @@ MakeTimingModel::makeTimingModel()
   makePorts();
 
   sta_->searchPreamble();
-  graph_ = sta_->graph();
 
   findTimingFromInputs();
   findClkedOutputPaths();
diff --git a/search/Sta.cc b/search/Sta.cc
index 08e82c7c..c0c40fa6 100644
--- a/search/Sta.cc
+++ b/search/Sta.cc
@@ -5626,6 +5626,7 @@ Sta::writeTimingModel(const char *lib_name,
                       const Corner *corner)
 {
   ensureLinked();
+  ensureGraph();
   LibertyLibrary *library = makeTimingModel(lib_name, cell_name, filename,
                                             corner, this);
   writeLiberty(library, filename, this);