diff --git a/cmd/nut_exporter/main.go b/cmd/nut_exporter/main.go
index b3914cf..35183d1 100644
--- a/cmd/nut_exporter/main.go
+++ b/cmd/nut_exporter/main.go
@@ -1,3 +1,5 @@
+// Command nut_exporter exports UPSs on one or more NUT servers to
+// Prometheus.
 package main
 
 import (