@@ -36,6 +36,14 @@ func NewArgs(initialArgs ...KeyValuePair) Args {

 	return args

 }

+func (args Args) Keys() []string {

+	keys := make([]string, 0, len(args.fields))

+	for k := range args.fields {

+		keys = append(keys, k)

+	}

+	return keys

+}

+

 // MarshalJSON returns a JSON byte representation of the Args

 func (args Args) MarshalJSON() ([]byte, error) {

 	if len(args.fields) == 0 {

@@ -2,6 +2,8 @@ package config

 import (

 	"encoding/json"

+	"fmt"

+	"sort"

 	"strings"

 	"github.com/docker/docker/api/types/filters"

@@ -16,6 +18,20 @@ type BuilderGCRule struct {

 type BuilderGCFilter filters.Args

+func (x *BuilderGCFilter) MarshalJSON() ([]byte, error) {

+	f := filters.Args(*x)

+	keys := f.Keys()

+	sort.Strings(keys)

+	arr := make([]string, 0, len(keys))

+	for _, k := range keys {

+		values := f.Get(k)

+		for _, v := range values {

+			arr = append(arr, fmt.Sprintf("%s=%s", k, v))

+		}

+	}

+	return json.Marshal(arr)

+}

+

 func (x *BuilderGCFilter) UnmarshalJSON(data []byte) error {

 	var arr []string

 	f := filters.NewArgs()