diff --git a/include/sta/ConcreteNetwork.hh b/include/sta/ConcreteNetwork.hh
index 1dde908b..4ae437d9 100644
--- a/include/sta/ConcreteNetwork.hh
+++ b/include/sta/ConcreteNetwork.hh
@@ -163,6 +163,7 @@ public:
 			       const char *filename);
   virtual LibertyLibrary *makeLibertyLibrary(const char *name,
 					     const char *filename);
+  virtual void deleteLibrary(Library *library);
   virtual Cell *makeCell(Library *library,
 			 const char *name,
 			 bool is_leaf,
@@ -238,7 +239,6 @@ public:
 
 protected:
   void addLibrary(ConcreteLibrary *library);
-  void deleteLibrary(ConcreteLibrary *library);
   void setName(const char *name);
   void clearConstantNets();
   virtual void visitConnectedPins(const Net *net,
diff --git a/include/sta/Network.hh b/include/sta/Network.hh
index 1b1c66c5..32178fea 100644
--- a/include/sta/Network.hh
+++ b/include/sta/Network.hh
@@ -533,6 +533,7 @@ public:
   virtual void setLinkFunc(LinkNetworkFunc *link) = 0;
   virtual Library *makeLibrary(const char *name,
 			       const char *filename) = 0;
+  virtual void deleteLibrary(Library *library) = 0;
   // Search the libraries in read order for a cell by name.
   virtual Cell *findAnyCell(const char *name) = 0;
   virtual Cell *makeCell(Library *library,
diff --git a/network/ConcreteNetwork.cc b/network/ConcreteNetwork.cc
index 51f059f7..6f8b8425 100644
--- a/network/ConcreteNetwork.cc
+++ b/network/ConcreteNetwork.cc
@@ -437,11 +437,12 @@ ConcreteNetwork::findLibrary(const char *name)
 }
 
 void
-ConcreteNetwork::deleteLibrary(ConcreteLibrary *library)
+ConcreteNetwork::deleteLibrary(Library *library)
 {
-  library_map_.erase(library->name());
-  library_seq_.eraseObject(library);
-  delete library;
+  ConcreteLibrary *clib = reinterpret_cast<ConcreteLibrary*>(library);
+  library_map_.erase(clib->name());
+  library_seq_.eraseObject(clib);
+  delete clib;
 }
 
 const char *