diff --git a/liberty/Liberty.cc b/liberty/Liberty.cc
index 0b3a3d5c..280863f7 100644
--- a/liberty/Liberty.cc
+++ b/liberty/Liberty.cc
@@ -1058,7 +1058,8 @@ LibertyCell::isBuffer() const
   LibertyPort *output;
   bufferPorts(input, output);
   return input && output
-    && hasBufferFunc(input, output);
+    && hasBufferFunc(input, output)
+    && !is_level_shifter_;
 }
 
 bool