diff --git a/ast/misc.go b/ast/misc.go
index 62b7da85d..66d079d39 100755
--- a/ast/misc.go
+++ b/ast/misc.go
@@ -790,16 +790,14 @@ func (n *SetRoleStmt) Restore(ctx *RestoreCtx) error {
 	case SetRoleAllExcept:
 		ctx.WriteKeyWord(" ALL EXCEPT")
 	}
-	if len(n.RoleList) > 0 {
-		for i, role := range n.RoleList {
-			ctx.WritePlain(" ")
-			err := role.Restore(ctx)
-			if err != nil {
-				return errors.Annotate(err, "An error occurred while restore SetRoleStmt.RoleList")
-			}
-			if i != len(n.RoleList)-1 {
-				ctx.WritePlain(",")
-			}
+	for i, role := range n.RoleList {
+		ctx.WritePlain(" ")
+		err := role.Restore(ctx)
+		if err != nil {
+			return errors.Annotate(err, "An error occurred while restore SetRoleStmt.RoleList")
+		}
+		if i != len(n.RoleList)-1 {
+			ctx.WritePlain(",")
 		}
 	}
 	return nil
diff --git a/go.mod1 b/go.mod1
index c2006d20d..dd28256d7 100755
--- a/go.mod1
+++ b/go.mod1
@@ -11,7 +11,6 @@ require (
 	github.com/pingcap/errors v0.11.0
 	github.com/pingcap/tidb v0.0.0-20190218065808-69472bd1a6e9
 	github.com/pingcap/tipb v0.0.0-20190107072121-abbec73437b7
-	github.com/shirou/gopsutil v2.18.12+incompatible // indirect
 	github.com/sirupsen/logrus v1.3.0
 	golang.org/x/text v0.3.1-0.20180807135948-17ff2d5776d2
 )