diff --git a/server/store/mongo.go b/server/store/mongo.go
index 752d4058c7936eb67b98d205775fba95b2f8a891..9773da778b041c0b63d0a28e729f6fd2189fd8a3 100644
--- a/server/store/mongo.go
+++ b/server/store/mongo.go
@@ -32,6 +32,7 @@ func parseMongoConfig(config string) *mgo.DialInfo {
 	return d
 }
 
+// NewMongoStore returns a MongoDB CertStorer.
 func NewMongoStore(config string) (CertStorer, error) {
 	session, err := mgo.DialWithInfo(parseMongoConfig(config))
 	if err != nil {