diff --git a/readme.md b/readme.md
index f00fc52..312d00b 100644
--- a/readme.md
+++ b/readme.md
@@ -12,3 +12,5 @@ The pigipio C library is specifically coded for the Raspberry Pi but might be ad
 assuming they would be pigio C, compatiable.  You must have pigpio C library installed first.
 
 When a gpio pin so set up is tripped this class emits a "fired" message.   If you pass a handler function it will be called when the "fired" message is emitted or you can set up your own "fired" listener to do as you please.
+
+You'll need to refer to https://github.com/fivdi/pigpio  to make sure you have the pigpio C library set up.