diff --git a/pkg/de-p1st-rotate/etc/de-p1st-rotate/config.cfg b/pkg/de-p1st-rotate/etc/de-p1st-rotate/config.cfg
index 4dbdad5..954eb68 100644
--- a/pkg/de-p1st-rotate/etc/de-p1st-rotate/config.cfg
+++ b/pkg/de-p1st-rotate/etc/de-p1st-rotate/config.cfg
@@ -1,4 +1,5 @@
-# The screen to rotate
+# The screen to rotate.
+# One can list all screens with "xrandr --listmonitors".
 SCREEN=eDP-1  # other values could be "eDP1" or "HDMI1"
 
 # xinput devices to rotate together with the screen.