diff --git a/os/gsession/gsession.go b/os/gsession/gsession.go
index ee1d15fc9..07b0661c5 100644
--- a/os/gsession/gsession.go
+++ b/os/gsession/gsession.go
@@ -14,6 +14,7 @@ import (
 )
 
 var (
+	// ErrorDisabled is used for marking certain interface function not used.
 	ErrorDisabled = gerror.NewOption(gerror.Option{
 		Text: "this feature is disabled in this storage",
 		Code: gcode.CodeNotSupported,