diff --git a/vendor/cmd/go/internal/modfile/read.go b/vendor/cmd/go/internal/modfile/read.go
index 8963fc2..1d81ff1 100644
--- a/vendor/cmd/go/internal/modfile/read.go
+++ b/vendor/cmd/go/internal/modfile/read.go
@@ -91,9 +91,10 @@
 
 func (x *FileSyntax) addLine(hint Expr, tokens ...string) *Line {
 	if hint == nil {
-		// If no hint given, add to the first statement of the given type.
+		// If no hint given, add to the last statement of the given type.
 	Loop:
-		for _, stmt := range x.Stmt {
+		for i := len(x.Stmt) - 1; i >= 0; i-- {
+			stmt := x.Stmt[i]
 			switch stmt := stmt.(type) {
 			case *Line:
 				if stmt.Token != nil && stmt.Token[0] == tokens[0] {
diff --git a/vendor/cmd/go/internal/modfile/rule_test.go b/vendor/cmd/go/internal/modfile/rule_test.go
new file mode 100644
index 0000000..b88ad62
--- /dev/null
+++ b/vendor/cmd/go/internal/modfile/rule_test.go
@@ -0,0 +1,90 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package modfile
+
+import (
+	"bytes"
+	"fmt"
+	"testing"
+)
+
+var addRequireTests = []struct {
+	in   string
+	path string
+	vers string
+	out  string
+}{
+	{
+		`
+		module m
+		require x.y/z v1.2.3
+		`,
+		"x.y/z", "v1.5.6",
+		`
+		module m
+		require x.y/z v1.5.6
+		`,
+	},
+	{
+		`
+		module m
+		require x.y/z v1.2.3
+		`,
+		"x.y/w", "v1.5.6",
+		`
+		module m
+		require (
+			x.y/z v1.2.3
+			x.y/w v1.5.6
+		)
+		`,
+	},
+	{
+		`
+		module m
+		require x.y/z v1.2.3
+		require x.y/q/v2 v2.3.4
+		`,
+		"x.y/w", "v1.5.6",
+		`
+		module m
+		require x.y/z v1.2.3
+		require (
+			x.y/q/v2 v2.3.4
+			x.y/w v1.5.6
+		)
+		`,
+	},
+}
+
+func TestAddRequire(t *testing.T) {
+	for i, tt := range addRequireTests {
+		t.Run(fmt.Sprintf("#%d", i), func(t *testing.T) {
+			f, err := Parse("in", []byte(tt.in), nil)
+			if err != nil {
+				t.Fatal(err)
+			}
+			g, err := Parse("out", []byte(tt.out), nil)
+			if err != nil {
+				t.Fatal(err)
+			}
+			golden, err := g.Format()
+			if err != nil {
+				t.Fatal(err)
+			}
+
+			if err := f.AddRequire(tt.path, tt.vers); err != nil {
+				t.Fatal(err)
+			}
+			out, err := f.Format()
+			if err != nil {
+				t.Fatal(err)
+			}
+			if !bytes.Equal(out, golden) {
+				t.Errorf("have:\n%s\nwant:\n%s", out, golden)
+			}
+		})
+	}
+}