diff --git a/src/dbSta/src/CMakeLists.txt b/src/dbSta/src/CMakeLists.txt
index ad52352fb96..b8117c53867 100644
--- a/src/dbSta/src/CMakeLists.txt
+++ b/src/dbSta/src/CMakeLists.txt
@@ -17,12 +17,6 @@ target_include_directories(dbSta_lib
   PUBLIC
     ../include
     ${PROJECT_SOURCE_DIR}/include
-  PRIVATE
-    # Needed for search/Levelize.hh and the unprefixed transitive
-    # OpenSTA headers it includes (e.g. Graph.hh) which are not part of
-    # OpenSTA's public include.
-    ${OPENSTA_HOME}
-    ${OPENSTA_HOME}/include/sta
 )
 
 
diff --git a/src/dbSta/src/dbSta.cc b/src/dbSta/src/dbSta.cc
index f77ea2ba261..369bc27d2f8 100644
--- a/src/dbSta/src/dbSta.cc
+++ b/src/dbSta/src/dbSta.cc
@@ -37,7 +37,6 @@
 #include "odb/dbBlockCallBackObj.h"
 #include "odb/dbObject.h"
 #include "odb/dbTypes.h"
-#include "search/Levelize.hh"
 #include "sta/ArcDelayCalc.hh"
 #include "sta/Clock.hh"
 #include "sta/Delay.hh"
@@ -45,6 +44,7 @@
 #include "sta/Graph.hh"
 #include "sta/GraphCmp.hh"
 #include "sta/GraphDelayCalc.hh"
+#include "sta/LevelizeObserver.hh"
 #include "sta/Liberty.hh"
 #include "sta/MinMax.hh"
 #include "sta/Mode.hh"
@@ -297,24 +297,23 @@ void dbSta::makeSdcNetwork()
   sdc_network_ = new dbSdcNetwork(network_);
 }
 
-// Levelize::setObserver takes ownership and deletes the prior observer,
-// so this composite must replicate the StaLevelizeObserver behavior that
-// Sta::makeObservers installs (forwarding to Search and GraphDelayCalc)
-// in addition to invalidating dbSta's cache.
-class DbStaLevelizeObserver : public LevelizeObserver
+// Extend the default StaLevelizeObserver (Search + GraphDelayCalc forwarding)
+// to also invalidate dbSta's driver-vertex cache.
+class DbStaLevelizeObserver : public StaLevelizeObserver
 {
  public:
-  explicit DbStaLevelizeObserver(dbSta* sta) : sta_(sta) {}
+  DbStaLevelizeObserver(dbSta* sta, Search* search, GraphDelayCalc* gdc)
+      : StaLevelizeObserver(search, gdc), sta_(sta)
+  {
+  }
   void levelsChangedBefore() override
   {
-    sta_->search()->levelsChangedBefore();
-    sta_->graphDelayCalc()->levelsChangedBefore();
+    StaLevelizeObserver::levelsChangedBefore();
     sta_->invalidateLevelizedDrvrVertices();
   }
   void levelChangedBefore(Vertex* vertex) override
   {
-    sta_->search()->levelChangedBefore(vertex);
-    sta_->graphDelayCalc()->levelChangedBefore(vertex);
+    StaLevelizeObserver::levelChangedBefore(vertex);
     sta_->invalidateLevelizedDrvrVertices();
   }
 
@@ -325,7 +324,8 @@ class DbStaLevelizeObserver : public LevelizeObserver
 void dbSta::makeObservers()
 {
   Sta::makeObservers();
-  levelize_->setObserver(new DbStaLevelizeObserver(this));
+  setLevelizeObserver(
+      new DbStaLevelizeObserver(this, search_, graph_delay_calc_));
 }
 
 void dbSta::invalidateLevelizedDrvrVertices()