diff --git a/bumblebee/modules/arch-update.py b/bumblebee/modules/arch-update.py
index faae680..f0bc70f 100644
--- a/bumblebee/modules/arch-update.py
+++ b/bumblebee/modules/arch-update.py
@@ -1,4 +1,8 @@
 """Check updates to Arch Linux.
+
+Requires the following executable:
+    * checkupdates (from pacman-contrib)
+
 """