diff --git a/tools/x86_trace_generator/README b/tools/x86_trace_generator/README
index f982d5bd..6fda5fec 100644
--- a/tools/x86_trace_generator/README
+++ b/tools/x86_trace_generator/README
@@ -11,7 +11,8 @@ How to generate x86 traces
 
      [1] Install Pin  (https://software.intel.com/content/www/us/en/develop/articles/pin-a-dynamic-binary-instrumentation-tool.html) 
      [2] go to macsim/tools/x86_trace_generator directory 
-     [3] set up $PIN_ROOT the root directory of pin  and copy libzilb.a in  
+     [3] export PIN_ROOT and PIN_HOME as the root directory of your pin install and copy libzlib.a 
+          into $PIN_ROOT/intel64/lib/ and $PIN_ROOT/extras/xed-intel64/lib
      [4] make 
      [5] pin -t obj-intel64/trace_generator.so - $BIN $ARGS