diff --git a/vlib/v/ast/ast.v b/vlib/v/ast/ast.v
index 441259d3f0..8101ea6bbc 100644
--- a/vlib/v/ast/ast.v
+++ b/vlib/v/ast/ast.v
@@ -162,9 +162,7 @@ pub:
 mut:
 // func         Expr
 	name        string
-	args        []Expr
-	arg_types   []table.Type
-	expr_types  []table.Type
+	args        []CallArg
 	is_c        bool
 	muts        []bool
 	or_block    OrExpr
@@ -177,15 +175,21 @@ pub:
 	pos           token.Position
 	expr          Expr // `user` in `user.register()`
 	name          string
-	args          []Expr
-	muts          []bool
+	args          []CallArg
 	or_block      OrExpr
 mut:
 	expr_type     table.Type // type of `user`
 	receiver_type table.Type // User
 	return_type   table.Type
-	arg_types     []table.Type
-	expr_types    []table.Type
+}
+
+pub struct CallArg {
+pub:
+	is_mut bool
+	expr   Expr
+mut:
+	typ           table.Type
+	expected_type table.Type
 }
 
 pub struct Return {
diff --git a/vlib/v/checker/checker.v b/vlib/v/checker/checker.v
index 7b5ef47573..dc1aac8fe7 100644
--- a/vlib/v/checker/checker.v
+++ b/vlib/v/checker/checker.v
@@ -229,8 +229,8 @@ pub fn (c mut Checker) call_expr(call_expr mut ast.CallExpr) table.Type {
 	}
 	call_expr.return_type = f.return_type
 	if f.is_c || call_expr.is_c {
-		for expr in call_expr.args {
-			c.expr(expr)
+		for arg in call_expr.args {
+			c.expr(arg.expr)
 		}
 		return f.return_type
 	}
@@ -242,18 +242,15 @@ pub fn (c mut Checker) call_expr(call_expr mut ast.CallExpr) table.Type {
 	}
 	// println can print anything
 	if fn_name == 'println' {
-		call_expr.arg_types = [c.expr(call_expr.args[0])]
+		call_expr.args[0].typ = c.expr(call_expr.args[0].expr)
 		return f.return_type
 	}
-	mut arg_types := []table.Type
-	mut expr_types := []table.Type
-	for i, arg_expr in call_expr.args {
+	for i, call_arg in call_expr.args {
 		arg := if f.is_variadic && i >= f.args.len - 1 { f.args[f.args.len - 1] } else { f.args[i] }
 		c.expected_type = arg.typ
-		typ := c.expr(arg_expr)
-		expr_types << typ
-		// arg_types << typ // arg.typ
-		arg_types << arg.typ
+		typ := c.expr(call_arg.expr)
+		call_expr.args[i].typ = typ
+		call_expr.args[i].expected_type = arg.typ
 		typ_sym := c.table.get_type_symbol(typ)
 		arg_typ_sym := c.table.get_type_symbol(arg.typ)
 		if !c.table.check(typ, arg.typ) {
@@ -270,8 +267,6 @@ pub fn (c mut Checker) call_expr(call_expr mut ast.CallExpr) table.Type {
 			c.error('!cannot use type `$typ_sym.str()` as type `$arg_typ_sym.str()` in argument ${i+1} to `$fn_name`', call_expr.pos)
 		}
 	}
-	call_expr.arg_types = arg_types
-	call_expr.expr_types = expr_types
 	return f.return_type
 }
 
@@ -281,8 +276,6 @@ pub fn (c mut Checker) method_call_expr(method_call_expr mut ast.MethodCallExpr)
 	method_call_expr.expr_type = typ
 	typ_sym := c.table.get_type_symbol(typ)
 	name := method_call_expr.name
-	mut arg_types := []table.Type
-	mut expr_types := []table.Type
 	// println('method call $name $method_call_expr.pos.line_nr')
 	if typ_sym.kind == .array && name in ['filter', 'clone', 'repeat'] {
 		if name == 'filter' {
@@ -294,7 +287,7 @@ pub fn (c mut Checker) method_call_expr(method_call_expr mut ast.MethodCallExpr)
 			})
 		}
 		else if name == 'repeat' {
-			c.expr(method_call_expr.args[0])
+			c.expr(method_call_expr.args[0].expr)
 		}
 		// need to return `array_xxx` instead of `array`
 		method_call_expr.return_type = typ
@@ -316,15 +309,13 @@ pub fn (c mut Checker) method_call_expr(method_call_expr mut ast.MethodCallExpr)
 		// if name == 'clone' {
 		// println('CLONE nr args=$method.args.len')
 		// }
-		for i, arg_expr in method_call_expr.args {
+		for i, arg in method_call_expr.args {
 			c.expected_type = method.args[i + 1].typ
-			arg_types << c.expected_type
-			expr_types << c.expr(arg_expr)
+			method_call_expr.args[i].expected_type = c.expected_type
+			method_call_expr.args[i].typ = c.expr(arg.expr)
 		}
 		method_call_expr.receiver_type = method.args[0].typ
 		method_call_expr.return_type = method.return_type
-		method_call_expr.arg_types = arg_types
-		method_call_expr.expr_types = expr_types
 		return method.return_type
 	}
 	c.error('type `$typ_sym.name` has no method `$name`', method_call_expr.pos)
diff --git a/vlib/v/fmt/fmt.v b/vlib/v/fmt/fmt.v
index 5e7ba1efdf..eaf5e05c51 100644
--- a/vlib/v/fmt/fmt.v
+++ b/vlib/v/fmt/fmt.v
@@ -364,7 +364,7 @@ fn (f mut Fmt) expr(node ast.Expr) {
 		}
 		ast.CallExpr {
 			f.write('${it.name}(')
-			f.call_args(it.args, it.muts)
+			f.call_args(it.args)
 			f.write(')')
 			f.or_expr(it.or_block)
 		}
@@ -490,7 +490,7 @@ fn (f mut Fmt) expr(node ast.Expr) {
 		ast.MethodCallExpr {
 			f.expr(it.expr)
 			f.write('.' + it.name + '(')
-			f.call_args(it.args, it.muts)
+			f.call_args(it.args)
 			f.write(')')
 			f.or_expr(it.or_block)
 		}
@@ -561,15 +561,15 @@ fn (f mut Fmt) wrap_long_line() {
 	}
 }
 
-fn (f mut Fmt) call_args(args []ast.Expr, muts []bool) {
+fn (f mut Fmt) call_args(args []ast.CallArg) {
 	for i, arg in args {
-		if muts[i] {
+		if arg.is_mut {
 			f.write('mut ')
 		}
 		if i > 0 {
 			f.wrap_long_line()
 		}
-		f.expr(arg)
+		f.expr(arg.expr)
 		if i < args.len - 1 {
 			f.write(', ')
 		}
diff --git a/vlib/v/gen/cgen.v b/vlib/v/gen/cgen.v
index cb2c5ebbed..d5c73f25b3 100644
--- a/vlib/v/gen/cgen.v
+++ b/vlib/v/gen/cgen.v
@@ -548,15 +548,15 @@ fn (g mut Gen) expr(node ast.Expr) {
 				name = name[3..]
 			}
 			g.write('${name}(')
-			if name == 'println' && it.arg_types[0] != table.string_type_idx {
+			if name == 'println' && it.args[0].typ != table.string_type_idx {
 				// `println(int_str(10))`
-				sym := g.table.get_type_symbol(it.arg_types[0])
+				sym := g.table.get_type_symbol(it.args[0].typ)
 				g.write('${sym.name}_str(')
-				g.expr(it.args[0])
+				g.expr(it.args[0].expr)
 				g.write('))')
 			}
 			else {
-				g.call_args(it.args, it.muts, it.arg_types, it.expr_types)
+				g.call_args(it.args)
 				g.write(')')
 			}
 			g.is_c_call = false
@@ -778,7 +778,7 @@ fn (g mut Gen) expr(node ast.Expr) {
 			}
 			*/
 			// ///////
-			g.call_args(it.args, it.muts, it.arg_types, it.expr_types)
+			g.call_args(it.args)
 			g.write(')')
 		}
 		ast.None {
@@ -1125,13 +1125,12 @@ fn (g mut Gen) const_decl(node ast.ConstDecl) {
 	}
 }
 
-fn (g mut Gen) call_args(args []ast.Expr, muts []bool, arg_types []table.Type, expr_types []table.Type) {
-	for i, expr in args {
-		if arg_types.len > 0 {
-			// typ := arg_types[i]
-			arg_is_ptr := table.type_is_ptr(arg_types[i]) || arg_types[i] == table.voidptr_type_idx
-			expr_is_ptr := i < expr_types.len && table.type_is_ptr(expr_types[i])
-			if muts[i] && !arg_is_ptr {
+fn (g mut Gen) call_args(args []ast.CallArg) {
+	for i, arg in args {
+		if arg.expected_type != 0 {
+			arg_is_ptr := table.type_is_ptr(arg.expected_type) || arg.expected_type == table.voidptr_type_idx
+			expr_is_ptr := table.type_is_ptr(arg.typ)
+			if arg.is_mut && !arg_is_ptr {
 				g.write('&/*mut*/')
 			}
 			else if arg_is_ptr && !expr_is_ptr {
@@ -1142,7 +1141,7 @@ fn (g mut Gen) call_args(args []ast.Expr, muts []bool, arg_types []table.Type, e
 				g.write('*/*d*/')
 			}
 		}
-		g.expr(expr)
+		g.expr(arg.expr)
 		if i != args.len - 1 {
 			g.write(', ')
 		}
diff --git a/vlib/v/gen/jsgen.v b/vlib/v/gen/jsgen.v
index ec6c904fe0..23be14a5c9 100644
--- a/vlib/v/gen/jsgen.v
+++ b/vlib/v/gen/jsgen.v
@@ -141,8 +141,8 @@ fn (g mut JsGen) expr(node ast.Expr) {
 		}
 		ast.CallExpr {
 			g.write('${it.name}(')
-			for i, expr in it.args {
-				g.expr(expr)
+			for i, arg in it.args {
+				g.expr(arg.expr)
 				if i != it.args.len - 1 {
 					g.write(', ')
 				}
diff --git a/vlib/v/gen/x64/gen.v b/vlib/v/gen/x64/gen.v
index ec7e39a505..71943ce6b9 100644
--- a/vlib/v/gen/x64/gen.v
+++ b/vlib/v/gen/x64/gen.v
@@ -361,7 +361,7 @@ fn (g mut Gen) expr(node ast.Expr) {
 		ast.StructInit {}
 		ast.CallExpr {
 			if it.name == 'println' || it.name == 'print' {
-				expr := it.args[0]
+				expr := it.args[0].expr
 				g.gen_print_from_expr(expr)
 			}
 			/*
diff --git a/vlib/v/parser/fn.v b/vlib/v/parser/fn.v
index 6ae198ef4e..e543a7e9c3 100644
--- a/vlib/v/parser/fn.v
+++ b/vlib/v/parser/fn.v
@@ -13,7 +13,7 @@ pub fn (p mut Parser) call_expr(is_c bool, mod string) ast.CallExpr {
 	name := p.check_name()
 	fn_name := if is_c { 'C.$name' } else if mod.len > 0 { '${mod}.$name' } else { name }
 	p.check(.lpar)
-	args,muts := p.call_args()
+	args := p.call_args()
 	mut or_stmts := []ast.Stmt
 	if p.tok.kind == .key_orelse {
 		p.next()
@@ -22,9 +22,7 @@ pub fn (p mut Parser) call_expr(is_c bool, mod string) ast.CallExpr {
 	node := ast.CallExpr{
 		name: fn_name
 		args: args
-		muts: muts
 		// tok: tok
-		
 		pos: tok.position()
 		is_c: is_c
 		or_block: ast.OrExpr{
@@ -34,25 +32,25 @@ pub fn (p mut Parser) call_expr(is_c bool, mod string) ast.CallExpr {
 	return node
 }
 
-pub fn (p mut Parser) call_args() ([]ast.Expr,[]bool) {
-	mut args := []ast.Expr
-	mut muts := []bool
+pub fn (p mut Parser) call_args() []ast.CallArg {
+	mut args := []ast.CallArg
 	for p.tok.kind != .rpar {
+		mut is_mut := false
 		if p.tok.kind == .key_mut {
 			p.check(.key_mut)
-			muts << true
-		}
-		else {
-			muts << false
+			is_mut = true
 		}
 		e := p.expr(0)
-		args << e
+		args << ast.CallArg{
+			is_mut: is_mut
+			expr: e
+		}
 		if p.tok.kind != .rpar {
 			p.check(.comma)
 		}
 	}
 	p.check(.rpar)
-	return args,muts
+	return args
 }
 
 fn (p mut Parser) fn_decl() ast.FnDecl {
diff --git a/vlib/v/parser/parser.v b/vlib/v/parser/parser.v
index d35f1ef6ef..3fea917919 100644
--- a/vlib/v/parser/parser.v
+++ b/vlib/v/parser/parser.v
@@ -891,7 +891,7 @@ fn (p mut Parser) dot_expr(left ast.Expr) ast.Expr {
 	pos := p.tok.position()
 	if p.tok.kind == .lpar {
 		p.next()
-		args,muts := p.call_args()
+		args := p.call_args()
 		mut or_stmts := []ast.Stmt
 		if p.tok.kind == .key_orelse {
 			p.next()
@@ -901,7 +901,6 @@ fn (p mut Parser) dot_expr(left ast.Expr) ast.Expr {
 			expr: left
 			name: field_name
 			args: args
-			muts: muts
 			pos: pos
 			or_block: ast.OrExpr{
 				stmts: or_stmts