diff --git a/internal/shaderir/glsl.go b/internal/shaderir/glsl.go
index c6315494a..16c0354b9 100644
--- a/internal/shaderir/glsl.go
+++ b/internal/shaderir/glsl.go
@@ -38,14 +38,14 @@ func (p *Program) Glsl() string {
 	p.structTypes = nil
 
 	var lines []string
-	for _, u := range p.Uniforms {
-		lines = append(lines, fmt.Sprintf("uniform %s;", p.glslVarDecl(&u.Type, u.Name)))
+	for i, t := range p.Uniforms {
+		lines = append(lines, fmt.Sprintf("uniform %s;", p.glslVarDecl(&t, fmt.Sprintf("U%d", i))))
 	}
-	for _, a := range p.Attributes {
-		lines = append(lines, fmt.Sprintf("attribute %s;", p.glslVarDecl(&a.Type, a.Name)))
+	for i, t := range p.Attributes {
+		lines = append(lines, fmt.Sprintf("attribute %s;", p.glslVarDecl(&t, fmt.Sprintf("A%d", i))))
 	}
-	for _, v := range p.Varyings {
-		lines = append(lines, fmt.Sprintf("varying %s;", p.glslVarDecl(&v.Type, v.Name)))
+	for i, t := range p.Varyings {
+		lines = append(lines, fmt.Sprintf("varying %s;", p.glslVarDecl(&t, fmt.Sprintf("V%d", i))))
 	}
 	for _, f := range p.Funcs {
 		lines = append(lines, p.glslFunc(&f)...)
@@ -121,6 +121,19 @@ func (p *Program) glslBlock(b *Block, f *Func, level int, localVarIndex int) []s
 		switch e.Type {
 		case Literal:
 			return e.Value
+		case VarName:
+			switch e.Variable.Type {
+			case Uniform:
+				return fmt.Sprintf("U%d", e.Variable.Index)
+			case Attribute:
+				return fmt.Sprintf("A%d", e.Variable.Index)
+			case Varying:
+				return fmt.Sprintf("V%d", e.Variable.Index)
+			case Local:
+				return fmt.Sprintf("l%d", e.Variable.Index)
+			default:
+				return fmt.Sprintf("?(unexpected variable type: %d)", e.Variable.Type)
+			}
 		case Ident:
 			return e.Value
 		case Unary:
diff --git a/internal/shaderir/ir_test.go b/internal/shaderir/ir_test.go
index f1ecc8311..ed34acb9b 100644
--- a/internal/shaderir/ir_test.go
+++ b/internal/shaderir/ir_test.go
@@ -20,6 +20,31 @@ import (
 	. "github.com/hajimehoshi/ebiten/internal/shaderir"
 )
 
+func assignStmt(lhs Expr, rhs Expr) Stmt {
+	return Stmt{
+		Type:  Assign,
+		Exprs: []Expr{lhs, rhs},
+	}
+}
+
+func varNameExpr(vt VariableType, index int) Expr {
+	return Expr{
+		Type: VarName,
+		Variable: Variable{
+			Type:  vt,
+			Index: index,
+		},
+	}
+}
+
+func binaryExpr(op Op, exprs ...Expr) Expr {
+	return Expr{
+		Type:  Binary,
+		Op:    op,
+		Exprs: exprs,
+	}
+}
+
 func TestOutput(t *testing.T) {
 	tests := []struct {
 		Name    string
@@ -34,11 +59,8 @@ func TestOutput(t *testing.T) {
 		{
 			Name: "Uniform",
 			Program: Program{
-				Uniforms: []Variable{
-					{
-						Name: "U0",
-						Type: Type{Main: Float},
-					},
+				Uniforms: []Type{
+					{Main: Float},
 				},
 			},
 			Glsl: `uniform float U0;`,
@@ -46,14 +68,11 @@ func TestOutput(t *testing.T) {
 		{
 			Name: "UniformStruct",
 			Program: Program{
-				Uniforms: []Variable{
+				Uniforms: []Type{
 					{
-						Name: "U0",
-						Type: Type{
-							Main: Struct,
-							Sub: []Type{
-								{Main: Float},
-							},
+						Main: Struct,
+						Sub: []Type{
+							{Main: Float},
 						},
 					},
 				},
@@ -66,23 +85,14 @@ uniform S0 U0;`,
 		{
 			Name: "Vars",
 			Program: Program{
-				Uniforms: []Variable{
-					{
-						Name: "U0",
-						Type: Type{Main: Float},
-					},
+				Uniforms: []Type{
+					{Main: Float},
 				},
-				Attributes: []Variable{
-					{
-						Name: "A0",
-						Type: Type{Main: Vec2},
-					},
+				Attributes: []Type{
+					{Main: Vec2},
 				},
-				Varyings: []Variable{
-					{
-						Name: "V0",
-						Type: Type{Main: Vec3},
-					},
+				Varyings: []Type{
+					{Main: Vec3},
 				},
 			},
 			Glsl: `uniform float U0;
@@ -212,29 +222,13 @@ varying vec3 V0;`,
 						},
 						Block: Block{
 							Stmts: []Stmt{
-								{
-									Type: Assign,
-									Exprs: []Expr{
-										{
-											Type:  Ident,
-											Value: "l2",
-										},
-										{
-											Type: Binary,
-											Op:   Add,
-											Exprs: []Expr{
-												{
-													Type:  Ident,
-													Value: "l0",
-												},
-												{
-													Type:  Ident,
-													Value: "l1",
-												},
-											},
-										},
-									},
-								},
+								assignStmt(
+									varNameExpr(Local, 2),
+									binaryExpr(Add,
+										varNameExpr(Local, 0),
+										varNameExpr(Local, 1),
+									),
+								),
 							},
 						},
 					},
diff --git a/internal/shaderir/program.go b/internal/shaderir/program.go
index 9eab2e08b..16a96685c 100644
--- a/internal/shaderir/program.go
+++ b/internal/shaderir/program.go
@@ -15,9 +15,9 @@
 package shaderir
 
 type Program struct {
-	Uniforms      []Variable
-	Attributes    []Variable
-	Varyings      []Variable
+	Uniforms      []Type
+	Attributes    []Type
+	Varyings      []Type
 	Funcs         []Func
 	VertexEntry   string
 	FragmentEntry string
@@ -26,11 +26,6 @@ type Program struct {
 	structTypes []Type
 }
 
-type Variable struct {
-	Name string
-	Type Type
-}
-
 type Func struct {
 	Name        string
 	InParams    []Type
@@ -69,16 +64,18 @@ const (
 )
 
 type Expr struct {
-	Type  ExprType
-	Exprs []Expr
-	Value string
-	Op    Op
+	Type     ExprType
+	Exprs    []Expr
+	Variable Variable
+	Value    string
+	Op       Op
 }
 
 type ExprType int
 
 const (
 	Literal ExprType = iota
+	VarName
 	Ident
 	Unary
 	Binary
@@ -87,6 +84,20 @@ const (
 	Index
 )
 
+type Variable struct {
+	Type  VariableType
+	Index int
+}
+
+type VariableType int
+
+const (
+	Uniform VariableType = iota
+	Attribute
+	Varying
+	Local
+)
+
 type Op string
 
 const (