diff --git a/prometheus/prometheus.go b/prometheus/prometheus.go
index 0a9947151..f79d24655 100644
--- a/prometheus/prometheus.go
+++ b/prometheus/prometheus.go
@@ -26,6 +26,7 @@ import (
 )
 
 const (
+	// namespace is prepended to each metric event name with "_"
 	defaultNamespace = "pilosa"
 )