diff --git a/C64_1351_Mouse/README.md b/C64_1351_Mouse/README.md
index 0880e21..2280db8 100644
--- a/C64_1351_Mouse/README.md
+++ b/C64_1351_Mouse/README.md
@@ -1,5 +1,9 @@
 ## USB mouse -> 1351 (C64) mouse adapter
 
+#### Library
+
+Install USB Host Shield Library 2.0 from Arduino IDE Library Manager.
+
 #### Pin 9 and 10 needed for TIMER1 - Move SS and INT of USB host shield library away
 
 C:\Users\xxxxx\Documents\Arduino\libraries\USB_Host_Shield_Library_2.0\UsbCore.h: