diff --git a/README.md b/README.md
index 5658dabbdcc55a7fa5b4ef043925c703530b8fe7..5bbc904ad167641e90699e572e410b5f6d22b1cf 100644
--- a/README.md
+++ b/README.md
@@ -63,7 +63,7 @@ gpio_modules:
 digital_outputs:
   - name: lights
     module: raspberrypi
-    pin: 21
+    pin: 21 # This is specified as the GPIO.BCM standard, not GPIO.BOARD
     on_payload: "ON"
     off_payload: "OFF"
     initial: low  # This optional value controls the initial state of the pin before receipt of any messages from MQTT. Valid options are 'low' and 'high'.