diff --git a/include/sta/ConcreteNetwork.hh b/include/sta/ConcreteNetwork.hh
index ad182ada..d9915e62 100644
--- a/include/sta/ConcreteNetwork.hh
+++ b/include/sta/ConcreteNetwork.hh
@@ -267,7 +267,7 @@ protected:
   void clearConstantNets();
   void visitConnectedPins(const Net *net,
                           PinVisitor &visitor,
-                          NetSet &visited_nets) const override;
+                          UnorderedSet<const Net*> &visited_nets) const override;
   Instance *makeConcreteInstance(ConcreteCell *cell,
 				 const char *name,
 				 Instance *parent);
diff --git a/include/sta/Network.hh b/include/sta/Network.hh
index 113ffe20..6ff808c8 100644
--- a/include/sta/Network.hh
+++ b/include/sta/Network.hh
@@ -32,6 +32,7 @@
 #include "VertexId.hh"
 #include "NetworkClass.hh"
 #include "StaState.hh"
+#include "UnorderedSet.hh"
 
 namespace sta {
 
@@ -470,7 +471,7 @@ protected:
   int hierarchyLevel(const Net *net) const;
   virtual void visitConnectedPins(const Net *net,
 				  PinVisitor &visitor,
-				  NetSet &visited_nets) const;
+				  UnorderedSet<const Net*> &visited_nets) const;
   // Default implementation uses linear search.
   virtual void findInstPinsMatching(const Instance *instance,
                                     const PatternMatch *pattern,
diff --git a/network/ConcreteNetwork.cc b/network/ConcreteNetwork.cc
index ed9c5d6c..f104dfbc 100644
--- a/network/ConcreteNetwork.cc
+++ b/network/ConcreteNetwork.cc
@@ -1549,7 +1549,7 @@ ConcreteNetwork::constantPinIterator()
 void
 ConcreteNetwork::visitConnectedPins(const Net *net,
 				    PinVisitor &visitor,
-				    NetSet &visited_nets) const
+				    UnorderedSet<const Net*> &visited_nets) const
 {
   if (!visited_nets.hasKey(net)) {
     visited_nets.insert(net);
diff --git a/network/Network.cc b/network/Network.cc
index d80b21ef..3f066cad 100644
--- a/network/Network.cc
+++ b/network/Network.cc
@@ -1307,7 +1307,7 @@ void
 Network::visitConnectedPins(const Pin *pin,
 			    PinVisitor &visitor) const
 {
-  NetSet visited_nets(network_);
+  UnorderedSet<const Net*> visited_nets;
   Net *pin_net = net(pin);
   Term *pin_term = term(pin);
   if (pin_net)
@@ -1328,14 +1328,14 @@ void
 Network::visitConnectedPins(const Net *net,
 			    PinVisitor &visitor) const
 {
-  NetSet visited_nets(this);
+  UnorderedSet<const Net*> visited_nets;
   visitConnectedPins(net, visitor, visited_nets);
 }
 
 void
 Network::visitConnectedPins(const Net *net,
 			    PinVisitor &visitor,
-			    NetSet &visited_nets) const
+			    UnorderedSet<const Net*> &visited_nets) const
 {
   if (!visited_nets.hasKey(net)) {
     visited_nets.insert(net);