diff --git a/.travis.yml b/.travis.yml
index 84821b41d..db0b950e3 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -9,9 +9,6 @@ notifications:
   on_success: never
   on_failure: never
 
-before_install:
-  - go get -u google.golang.org/grpc
-
 script:
   - GO111MODULE=on DRAGONBOAT_LOGDB=pebble make travis-ci-test
   - GO111MODULE=on go test -tags "dragonboat_pebble_test" -v -coverprofile=coverage.txt -covermode=atomic
diff --git a/internal/fileutil/utils.go b/internal/fileutil/utils.go
index 9afba770f..6f23ad668 100644
--- a/internal/fileutil/utils.go
+++ b/internal/fileutil/utils.go
@@ -28,8 +28,6 @@ import (
 	"sync"
 	"time"
 
-	"github.com/golang/protobuf/proto"
-
 	"github.com/lni/dragonboat/v3/internal/vfs"
 )
 
@@ -43,6 +41,15 @@ const (
 	deleteFilename       = "DELETED.dragonboat"
 )
 
+// Marshaler is the interface for types that can be Marshaled.
+type Marshaler interface {
+	Marshal() ([]byte, error)
+}
+
+type Unmarshaler interface {
+	Unmarshal([]byte) error
+}
+
 // DirExist returns whether the specified filesystem entry exists.
 func DirExist(name string, fs vfs.IFS) (bool, error) {
 	if name == "." || name == "/" {
@@ -152,7 +159,7 @@ func SyncDir(dir string, fs vfs.IFS) (err error) {
 }
 
 // MarkDirAsDeleted marks the specified directory as deleted.
-func MarkDirAsDeleted(dir string, msg proto.Message, fs vfs.IFS) error {
+func MarkDirAsDeleted(dir string, msg Marshaler, fs vfs.IFS) error {
 	return CreateFlagFile(dir, deleteFilename, msg, fs)
 }
 
@@ -175,7 +182,7 @@ func getHash(data []byte) []byte {
 // CreateFlagFile creates a flag file in the specific location. The flag file
 // contains the marshaled data of the specified protobuf message.
 func CreateFlagFile(dir string,
-	filename string, msg proto.Message, fs vfs.IFS) (err error) {
+	filename string, msg Marshaler, fs vfs.IFS) (err error) {
 	fp := fs.PathJoin(dir, filename)
 	f, err := fs.Create(fp)
 	if err != nil {
@@ -189,7 +196,7 @@ func CreateFlagFile(dir string,
 			err = cerr
 		}
 	}()
-	data, err := proto.Marshal(msg)
+	data, err := msg.Marshal()
 	if err != nil {
 		panic(err)
 	}
@@ -215,7 +222,7 @@ func CreateFlagFile(dir string,
 // location. The data of the flag file will be unmarshaled into the specified
 // protobuf message.
 func GetFlagFileContent(dir string,
-	filename string, msg proto.Message, fs vfs.IFS) (err error) {
+	filename string, msg Unmarshaler, fs vfs.IFS) (err error) {
 	fp := fs.PathJoin(dir, filename)
 	f, err := fs.Open(vfs.Clean(fp))
 	if err != nil {
@@ -239,7 +246,7 @@ func GetFlagFileContent(dir string,
 	if !bytes.Equal(h, expectedHash) {
 		panic("corrupted flag file content")
 	}
-	return proto.Unmarshal(buf, msg)
+	return msg.Unmarshal(buf)
 }
 
 // HasFlagFile returns a boolean value indicating whether flag file can be
diff --git a/internal/rsm/statemachine_test.go b/internal/rsm/statemachine_test.go
index 8d18234f9..dc95244c1 100644
--- a/internal/rsm/statemachine_test.go
+++ b/internal/rsm/statemachine_test.go
@@ -21,8 +21,6 @@ import (
 	"math/rand"
 	"testing"
 
-	"github.com/golang/protobuf/proto"
-
 	"github.com/lni/dragonboat/v3/client"
 	"github.com/lni/dragonboat/v3/config"
 	"github.com/lni/dragonboat/v3/internal/raft"
@@ -1259,7 +1257,7 @@ func genTestKVData(k, d string) []byte {
 		Key: k,
 		Val: d,
 	}
-	data, err := proto.Marshal(&u)
+	data, err := u.Marshal()
 	if err != nil {
 		panic(err)
 	}
diff --git a/internal/server/snapshotenv.go b/internal/server/snapshotenv.go
index 75c2d1bc7..8e76a3f89 100644
--- a/internal/server/snapshotenv.go
+++ b/internal/server/snapshotenv.go
@@ -24,8 +24,6 @@ import (
 	"sync"
 	"syscall"
 
-	"github.com/golang/protobuf/proto"
-
 	"github.com/lni/dragonboat/v3/internal/fileutil"
 	"github.com/lni/dragonboat/v3/internal/vfs"
 )
@@ -186,7 +184,7 @@ func (se *SSEnv) MustRemoveTempDir() {
 }
 
 // FinalizeSnapshot finalizes the snapshot.
-func (se *SSEnv) FinalizeSnapshot(msg proto.Message) error {
+func (se *SSEnv) FinalizeSnapshot(msg fileutil.Marshaler) error {
 	finalizeLock.Lock()
 	defer finalizeLock.Unlock()
 	if err := se.createFlagFile(msg); err != nil {
@@ -209,7 +207,7 @@ func (se *SSEnv) RemoveFinalDir() error {
 }
 
 // SaveSSMetadata saves the metadata of the snapshot file.
-func (se *SSEnv) SaveSSMetadata(msg proto.Message) error {
+func (se *SSEnv) SaveSSMetadata(msg fileutil.Marshaler) error {
 	err := fileutil.CreateFlagFile(se.tmpDir,
 		SnapshotMetadataFilename, msg, se.fs)
 	return err
@@ -278,7 +276,7 @@ func (se *SSEnv) renameTempDirToFinalDir() error {
 	return fileutil.SyncDir(se.rootDir, se.fs)
 }
 
-func (se *SSEnv) createFlagFile(msg proto.Message) error {
+func (se *SSEnv) createFlagFile(msg fileutil.Marshaler) error {
 	return fileutil.CreateFlagFile(se.tmpDir,
 		fileutil.SnapshotFlagFilename, msg, se.fs)
 }
diff --git a/internal/tests/concurrentkv.go b/internal/tests/concurrentkv.go
index f105b4dc8..fb8afb0d3 100644
--- a/internal/tests/concurrentkv.go
+++ b/internal/tests/concurrentkv.go
@@ -27,7 +27,6 @@ import (
 	"time"
 	"unsafe"
 
-	"github.com/golang/protobuf/proto"
 	"github.com/lni/dragonboat/v3/internal/tests/kvpb"
 	sm "github.com/lni/dragonboat/v3/statemachine"
 )
@@ -89,7 +88,7 @@ func (s *ConcurrentKVTest) Lookup(key interface{}) (interface{}, error) {
 func (s *ConcurrentKVTest) Update(ents []sm.Entry) ([]sm.Entry, error) {
 	for i := 0; i < len(ents); i++ {
 		dataKv := &kvpb.PBKV{}
-		err := proto.Unmarshal(ents[i].Cmd, dataKv)
+		err := dataKv.Unmarshal(ents[i].Cmd)
 		if err != nil {
 			panic(err)
 		}
diff --git a/internal/tests/kvtest.go b/internal/tests/kvtest.go
index d6dd29041..e3d00c4cf 100644
--- a/internal/tests/kvtest.go
+++ b/internal/tests/kvtest.go
@@ -34,7 +34,6 @@ import (
 	"sync"
 	"time"
 
-	"github.com/golang/protobuf/proto"
 	"github.com/lni/dragonboat/v3/internal/tests/kvpb"
 	sm "github.com/lni/dragonboat/v3/statemachine"
 	"github.com/lni/goutils/random"
@@ -153,7 +152,7 @@ func (s *KVTest) Update(data []byte) (sm.Result, error) {
 	}
 	generateRandomDelay()
 	dataKv := s.pbkvPool.Get().(*kvpb.PBKV)
-	err := proto.Unmarshal(data, dataKv)
+	err := dataKv.Unmarshal(data)
 	if err != nil {
 		panic(err)
 	}