diff --git a/cmd/protobuild/cmd.go b/cmd/protobuild/cmd.go
index 0ad630b..a12238f 100644
--- a/cmd/protobuild/cmd.go
+++ b/cmd/protobuild/cmd.go
@@ -3,7 +3,6 @@ package protobuild
 import (
 	"bytes"
 	"fmt"
-	"github.com/a8m/envsubst"
 	"io"
 	"io/fs"
 	"os"
@@ -12,7 +11,7 @@ import (
 	"strings"
 	"sync"
 
-	_ "github.com/a8m/envsubst"
+	"github.com/a8m/envsubst"
 	"github.com/cnf/structhash"
 	"github.com/pubgo/funk/assert"
 	"github.com/pubgo/funk/errors"
@@ -340,6 +339,10 @@ func Main() *cli.App {
 							continue
 						}
 
+						if pathutil.IsNotExist(url) && dep.Optional != nil && *dep.Optional {
+							continue
+						}
+
 						v := strutil.FirstFnNotEmpty(func() string {
 							return versions[url]
 						}, func() string {
@@ -422,6 +425,11 @@ func Main() *cli.App {
 						fmt.Println(url)
 
 						url = assert.Must1(filepath.Abs(url))
+
+						if pathutil.IsNotExist(url) && dep.Optional != nil && *dep.Optional {
+							continue
+						}
+
 						newUrl := filepath.Join(cfg.Vendor, dep.Name)
 						assert.Must(filepath.Walk(url, func(path string, info fs.FileInfo, err error) (gErr error) {
 							if err != nil {
diff --git a/cmd/protobuild/config.go b/cmd/protobuild/config.go
index 999686f..f87ea8c 100644
--- a/cmd/protobuild/config.go
+++ b/cmd/protobuild/config.go
@@ -39,8 +39,9 @@ type plugin struct {
 }
 
 type depend struct {
-	Name    string  `yaml:"name,omitempty"`
-	Url     string  `yaml:"url,omitempty"`
-	Path    string  `yaml:"path,omitempty"`
-	Version *string `yaml:"version,omitempty"`
+	Name     string  `yaml:"name,omitempty"`
+	Url      string  `yaml:"url,omitempty"`
+	Path     string  `yaml:"path,omitempty"`
+	Version  *string `yaml:"version,omitempty"`
+	Optional *bool   `yaml:"optional,omitempty"`
 }
diff --git a/version/version.go b/version/version.go
index d4ca7d8..7f743ae 100644
--- a/version/version.go
+++ b/version/version.go
@@ -5,7 +5,7 @@ import (
 	"github.com/pubgo/funk/assert"
 )
 
-var Version = "v0.0.1-dev"
+var Version = "v0.0.20"
 
 func init() {
 	if Version == "" {