diff --git a/README.md b/README.md
index 2d8776b0901b45210bc1b754c587c266625674e6..db959b96a3f0afdf0f966dea37cfabbb3484aad2 100644
--- a/README.md
+++ b/README.md
@@ -61,7 +61,7 @@ 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'.