diff --git a/liberty/Liberty.cc b/liberty/Liberty.cc
index 0eef87c4..cb4abe77 100644
--- a/liberty/Liberty.cc
+++ b/liberty/Liberty.cc
@@ -1029,21 +1029,11 @@ LibertyCell::setClockGateType(ClockGateType type)
 bool
 LibertyCell::isBuffer() const
 {
-  int input_count = 0;
-  int output_count = 0;
-  for (ConcretePort *cport : ports_) {
-    LibertyPort *port = static_cast<LibertyPort*>(cport);
-    PortDirection *dir = port->direction();
-    if (dir->isInput())
-      input_count++;
-    else if (dir->isOutput())
-      output_count++;
-    else if (!dir->isPowerGround())
-      return false;
-    if (input_count > 1 || output_count > 1)
-      break;
-  }
-  return input_count == 1 && output_count == 1;
+  LibertyPort *input;
+  LibertyPort *output;
+  bufferPorts(input, output);
+  return input && output
+    && hasBufferFunc(input, output);
 }
 
 bool
@@ -1059,19 +1049,36 @@ LibertyCell::hasBufferFunc(const LibertyPort *input,
 void
 LibertyCell::bufferPorts(// Return values.
 			 LibertyPort *&input,
-			 LibertyPort *&output)
+			 LibertyPort *&output) const
 {
   input = nullptr;
   output = nullptr;
   for (ConcretePort *cport : ports_) {
     LibertyPort *port = static_cast<LibertyPort*>(cport);
     PortDirection *dir = port->direction();
-    if (dir->isInput())
+    if (dir->isInput()) {
+      if (input) {
+	// More than one input.
+	input = nullptr;
+	output = nullptr;
+	break;
+      }
       input = port;
-    else if (dir->isOutput())
+    }
+    else if (dir->isOutput()) {
+      if (output) {
+	// More than one output.
+	input = nullptr;
+	output = nullptr;
+	break;
+      }
       output = port;
-    if (input && output)
-      return;
+    }
+    else if (!dir->isPowerGround()) {
+	input = nullptr;
+	output = nullptr;
+	break;
+    }
   }
 }
 
diff --git a/liberty/Liberty.hh b/liberty/Liberty.hh
index 6f45bc82..2bc16329 100644
--- a/liberty/Liberty.hh
+++ b/liberty/Liberty.hh
@@ -494,7 +494,7 @@ public:
   // Only valid when isBuffer() returns true.
   void bufferPorts(// Return values.
 		   LibertyPort *&input,
-		   LibertyPort *&output);
+		   LibertyPort *&output) const;
 
 protected:
   void addPort(ConcretePort *port);
diff --git a/network/ConcreteNetwork.cc b/network/ConcreteNetwork.cc
index 75f3cec8..5002f003 100644
--- a/network/ConcreteNetwork.cc
+++ b/network/ConcreteNetwork.cc
@@ -456,7 +456,19 @@ LibertyLibrary *
 ConcreteNetwork::findLiberty(const char *name)
 {
   ConcreteLibrary *lib =  library_map_.findKey(name);
-  return static_cast<LibertyLibrary*>(lib);
+  if (lib) {
+    if (lib->isLiberty())
+      return static_cast<LibertyLibrary*>(lib);
+    // Potential name conflict
+    else {
+      for (ConcreteLibrary *lib : library_seq_) {
+	if (stringEq(lib->name(), name)
+	    && lib->isLiberty())
+	  return static_cast<LibertyLibrary*>(lib);
+      }
+    }
+  }
+  return nullptr;
 }
 
 LibertyLibrary *