diff --git a/README.md b/README.md
index d6d86ea..9eacbdf 100644
--- a/README.md
+++ b/README.md
@@ -5,6 +5,12 @@ Uses the luminance sensor of a laptop to determine a target brightness, the user
 can further adjust the brightness between updates to give the program an offset
 to respect.
 
+## Check for Support
+
+This program needs an ambient light sensor, you can check if your device has one
+by running `cat /sys/bus/iio/devices/iio:device0/in_illuminance_raw` this should
+give a number and not an error
+
 ## Install
 
 Copy ambient.py to a directory in PATH: `sudo cp ambient.py /usr/local/bin`