diff --git a/cmd/greenmask/cmd/root.go b/cmd/greenmask/cmd/root.go
index b7f21f44..7c676879 100644
--- a/cmd/greenmask/cmd/root.go
+++ b/cmd/greenmask/cmd/root.go
@@ -140,6 +140,7 @@ func initConfig() {
 			mapstructure.StringToTimeDurationHookFunc(),
 			mapstructure.StringToSliceHookFunc(","),
 		)
+		cfg.ErrorUnused = true
 	}
 
 	if err := viper.Unmarshal(Config, decoderCfg); err != nil {