diff --git a/render/expected/expected.go b/render/expected/expected.go
index f6e7c22ad..6ce50bd9b 100644
--- a/render/expected/expected.go
+++ b/render/expected/expected.go
@@ -8,6 +8,7 @@ import (
 	"github.com/weaveworks/scope/test"
 )
 
+// Sterilize cleans up RenderableNodes test fixtures
 func Sterilize(r render.RenderableNodes) render.RenderableNodes {
 	// Since introducing new map fields to the report.NodeMetadata type, its
 	// zero value is •not valid• -- every time you need one, you need to use