diff --git a/modload/module.go b/modload/module.go
index ce70824..d0e738b 100644
--- a/modload/module.go
+++ b/modload/module.go
@@ -25,6 +25,7 @@ import (
 	"github.com/goplus/mod"
 	"github.com/goplus/mod/env"
 	"github.com/goplus/mod/modfile"
+	"github.com/goplus/mod/sumfile"
 	"github.com/qiniu/x/errors"
 	"golang.org/x/mod/module"
 
@@ -63,6 +64,14 @@ func (p Module) workFile() string {
 	return ""
 }
 
+func (p Module) sumFile() string {
+	if syn := p.Syntax; syn != nil {
+		dir, _ := filepath.Split(syn.Name)
+		return dir + "go.sum"
+	}
+	return ""
+}
+
 // Root returns absolute root path of this module.
 func (p Module) Root() string {
 	if syn := p.Syntax; syn != nil {
@@ -343,6 +352,9 @@ func (p Module) SaveWithGopMod(gop *env.Gop, flags int) (err error) {
 			return
 		}
 	}
+	if (flags & FlagDepModGop) == 0 {
+		return
+	}
 
 	var work *gomodfile.WorkFile
 	var workFile = p.workFile()
@@ -372,17 +384,23 @@ func (p Module) requireGop(gop *env.Gop, gopVer string, old, flags int) {
 		p.File.AddRequire(gopMod, gopVer)
 	}
 	if (flags&FlagDepModX) != 0 && (old&FlagDepModX) == 0 { // depends module github.com/qiniu/x
-		if x, ok := getXVer(gop); ok {
+		if x, xsum, ok := getXVer(gop); ok {
 			p.File.AddRequire(x.Path, x.Version)
+			if sumf, err := sumfile.Load(p.sumFile()); err == nil && sumf.Lookup(xMod) == nil {
+				sumf.Add(xsum)
+				sumf.Save()
+			}
 		}
 	}
 }
 
-func getXVer(gop *env.Gop) (modVer module.Version, ok bool) {
+func getXVer(gop *env.Gop) (modVer module.Version, xsum []string, ok bool) {
 	if mod, err := LoadFrom(gop.Root+"/go.mod", ""); err == nil {
 		for _, r := range mod.File.Require {
 			if r.Mod.Path == xMod {
-				return r.Mod, true
+				if sumf, err := sumfile.Load(gop.Root + "/go.sum"); err == nil {
+					return r.Mod, sumf.Lookup(xMod), true
+				}
 			}
 		}
 	}
diff --git a/modload/module_test.go b/modload/module_test.go
index 79b4143..fdb109d 100644
--- a/modload/module_test.go
+++ b/modload/module_test.go
@@ -139,6 +139,9 @@ func TestSaveDefault(t *testing.T) {
 	if v := Default.workFile(); v != "" {
 		t.Fatal("Default.workFile:", v)
 	}
+	if v := Default.sumFile(); v != "" {
+		t.Fatal("Default.sumFile:", v)
+	}
 	if err := Default.Save(); err != ErrSaveDefault {
 		t.Fatal("Default.Save:", err)
 	}
@@ -215,7 +218,7 @@ require (
 ` {
 		t.Fatal("SaveWithGopMod:", v)
 	}
-	if _, ok := getXVer(&env.Gop{Root: "/foo/bar"}); ok {
+	if _, _, ok := getXVer(&env.Gop{Root: "/foo/bar"}); ok {
 		t.Fatal("getXVer: ok?")
 	}
 
@@ -224,6 +227,10 @@ require (
 		log.Fatal("mod.SaveWithGopMod 3:", err)
 	}
 
+	if err = mod.SaveWithGopMod(&env.Gop{Version: "v1.2.0 devel", Root: ".gop"}, FlagDepModX); err != nil {
+		log.Fatal("mod.SaveWithGopMod 4:", err)
+	}
+
 	mod.Opt.Projects = append(mod.Opt.Projects, spxProject)
 	mod.Save()
 	b, err = os.ReadFile(mod.Opt.Syntax.Name)
diff --git a/sumfile/sumfile.go b/sumfile/sumfile.go
new file mode 100644
index 0000000..7c6e8bb
--- /dev/null
+++ b/sumfile/sumfile.go
@@ -0,0 +1,80 @@
+/*
+ * Copyright (c) 2024 The GoPlus Authors (goplus.org). All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package sumfile
+
+import (
+	"os"
+	"sort"
+	"strings"
+)
+
+type File struct {
+	lines []string
+	gosum string
+}
+
+func Load(gosum string) (sumf *File, err error) {
+	var lines []string
+	b, err := os.ReadFile(gosum)
+	if err != nil {
+		if !os.IsNotExist(err) {
+			return
+		}
+	} else {
+		text := string(b)
+		lines = strings.Split(strings.TrimRight(text, "\n"), "\n")
+	}
+	return &File{lines, gosum}, nil
+}
+
+func (p *File) Save() (err error) {
+	n := 0
+	for _, line := range p.lines {
+		n += 1 + len(line)
+	}
+	b := make([]byte, 0, n)
+	for _, line := range p.lines {
+		b = append(b, line...)
+		b = append(b, '\n')
+	}
+	return os.WriteFile(p.gosum, b, 0666)
+}
+
+func (p *File) Lookup(modPath string) []string {
+	prefix := modPath + " "
+	lines := p.lines
+	for i, line := range lines {
+		if line > prefix {
+			if strings.HasPrefix(line, prefix) {
+				for j, line := range lines[i+1:] {
+					if !strings.HasPrefix(line, prefix) {
+						lines = lines[:i+1+j]
+						break
+					}
+				}
+				return lines[i:]
+			}
+			break
+		}
+	}
+	return nil
+}
+
+func (p *File) Add(lines []string) {
+	p.lines = append(p.lines, lines...)
+	sort.Strings(p.lines)
+}