diff --git a/main.go b/main.go
index dc98021..4b54df2 100644
--- a/main.go
+++ b/main.go
@@ -1,6 +1,6 @@
 package main
 
-//go:generate goyacc gram.y
+//go:generate goyacc -l gram.y
 
 import (
 	"bufio"
diff --git a/y.go b/y.go
index e43daa2..a997052 100644
--- a/y.go
+++ b/y.go
@@ -1,18 +1,13 @@
-// Code generated by goyacc gram.y. DO NOT EDIT.
-
-//line gram.y:7
+// Code generated by goyacc -l gram.y. DO NOT EDIT.
 package main
 
 import __yyfmt__ "fmt"
 
-//line gram.y:7
-
 import (
 	"github.com/lufia/qsh/ast"
 	"github.com/lufia/qsh/build"
 )
 
-//line gram.y:14
 type yySymType struct {
 	yys  int
 	tree *ast.Node
@@ -57,7 +52,6 @@ const yyEofCode = 1
 const yyErrCode = 2
 const yyInitialStackSize = 16
 
-//line yacctab:1
 var yyExca = [...]int8{
 	-1, 0,
 	1, 1,
@@ -160,8 +154,6 @@ var yyErrorMessages = [...]struct {
 	msg   string
 }{}
 
-//line yaccpar:1
-
 /*	parser for yacc output	*/
 
 var (
@@ -493,13 +485,11 @@ yydefault:
 
 	case 1:
 		yyDollar = yyS[yypt-0 : yypt+1]
-//line gram.y:22
 		{
 			return 1
 		}
 	case 2:
 		yyDollar = yyS[yypt-2 : yypt+1]
-//line gram.y:26
 		{
 			if *flagDebug {
 				ast.Dump(yyDollar[1].tree)
@@ -509,128 +499,107 @@ yydefault:
 		}
 	case 4:
 		yyDollar = yyS[yypt-2 : yypt+1]
-//line gram.y:37
 		{
 			yyVAL.tree = ast.New(ast.LIST, yyDollar[1].tree, yyDollar[2].tree)
 		}
 	case 6:
 		yyDollar = yyS[yypt-2 : yypt+1]
-//line gram.y:44
 		{
 			yyVAL.tree = ast.New(ast.LIST, yyDollar[1].tree, yyDollar[2].tree)
 		}
 	case 8:
 		yyDollar = yyS[yypt-2 : yypt+1]
-//line gram.y:51
 		{
 			yyVAL.tree = ast.Async(yyDollar[1].tree)
 		}
 	case 11:
 		yyDollar = yyS[yypt-3 : yypt+1]
-//line gram.y:61
 		{
 			yyVAL.tree = ast.Block(yyDollar[2].tree)
 		}
 	case 12:
 		yyDollar = yyS[yypt-3 : yypt+1]
-//line gram.y:67
 		{
 			yyVAL.tree = ast.Assign(yyDollar[1].tree, yyDollar[3].tree)
 		}
 	case 13:
 		yyDollar = yyS[yypt-0 : yypt+1]
-//line gram.y:72
 		{
 			yyVAL.tree = nil
 		}
 	case 14:
 		yyDollar = yyS[yypt-3 : yypt+1]
-//line gram.y:76
 		{
 			yyVAL.tree = ast.New(ast.IF, yyDollar[2].tree, yyDollar[3].tree)
 		}
 	case 15:
 		yyDollar = yyS[yypt-5 : yypt+1]
-//line gram.y:80
 		{
 			p := ast.New(ast.LIST, yyDollar[2].tree, yyDollar[4].tree)
 			yyVAL.tree = ast.New(ast.FOR, p, yyDollar[5].tree)
 		}
 	case 16:
 		yyDollar = yyS[yypt-2 : yypt+1]
-//line gram.y:85
 		{
 			yyVAL.tree = ast.Load(yyDollar[2].tree)
 		}
 	case 17:
 		yyDollar = yyS[yypt-1 : yypt+1]
-//line gram.y:89
 		{
 			yyVAL.tree = ast.Simple(yyDollar[1].tree)
 		}
 	case 18:
 		yyDollar = yyS[yypt-3 : yypt+1]
-//line gram.y:93
 		{
 			yyVAL.tree = ast.New(ast.ANDAND, yyDollar[1].tree, yyDollar[3].tree)
 		}
 	case 19:
 		yyDollar = yyS[yypt-3 : yypt+1]
-//line gram.y:97
 		{
 			yyVAL.tree = ast.New(ast.OROR, yyDollar[1].tree, yyDollar[3].tree)
 		}
 	case 20:
 		yyDollar = yyS[yypt-3 : yypt+1]
-//line gram.y:101
 		{
 			yyVAL.tree = ast.New(ast.PIPE, yyDollar[1].tree, yyDollar[3].tree)
 		}
 	case 23:
 		yyDollar = yyS[yypt-2 : yypt+1]
-//line gram.y:109
 		{
 			yyVAL.tree = ast.New(ast.LIST, yyDollar[1].tree, yyDollar[2].tree)
 		}
 	case 24:
 		yyDollar = yyS[yypt-2 : yypt+1]
-//line gram.y:113
 		{
 			yyVAL.tree = ast.New(ast.LIST, yyDollar[1].tree, yyDollar[2].tree)
 		}
 	case 25:
 		yyDollar = yyS[yypt-2 : yypt+1]
-//line gram.y:119
 		{
 			yyVAL.tree = ast.Redirect(yyDollar[1].tree, yyDollar[2].tree)
 		}
 	case 28:
 		yyDollar = yyS[yypt-2 : yypt+1]
-//line gram.y:131
 		{
 			yyVAL.tree = ast.Var(yyDollar[2].tree)
 		}
 	case 29:
 		yyDollar = yyS[yypt-3 : yypt+1]
-//line gram.y:135
 		{
 			yyVAL.tree = ast.Tuple(yyDollar[2].tree)
 		}
 	case 30:
 		yyDollar = yyS[yypt-4 : yypt+1]
-//line gram.y:139
 		{
 			yyVAL.tree = ast.Module(yyDollar[3].tree)
 		}
 	case 32:
 		yyDollar = yyS[yypt-0 : yypt+1]
-//line gram.y:145
 		{
 			yyVAL.tree = nil
 		}
 	case 33:
 		yyDollar = yyS[yypt-2 : yypt+1]
-//line gram.y:149
 		{
 			if yyDollar[1].tree == nil {
 				yyVAL.tree = yyDollar[2].tree