diff --git a/internal/distributed/rootcoord/client/client.go b/internal/distributed/rootcoord/client/client.go
index 677e807dbf..f7070861c2 100644
--- a/internal/distributed/rootcoord/client/client.go
+++ b/internal/distributed/rootcoord/client/client.go
@@ -37,6 +37,7 @@ import (
 	"google.golang.org/grpc/codes"
 )
 
+// Base is an interface that embeds types.RootCoord and contains some other methods.
 type Base interface {
 	types.RootCoord