diff --git a/go.mod b/go.mod
index 4d667be..a08fc19 100644
--- a/go.mod
+++ b/go.mod
@@ -4,6 +4,6 @@ go 1.12
 
 require (
 	github.com/BurntSushi/toml v0.3.1
-	github.com/gomarkdown/markdown v0.0.0-20190912180731-281270bc6d83
+	github.com/gomarkdown/markdown v0.0.0-20191229055418-359dc4b9d66b
 	github.com/google/go-cmp v0.2.0
 )
diff --git a/go.sum b/go.sum
index 03c872e..5645624 100644
--- a/go.sum
+++ b/go.sum
@@ -1,7 +1,7 @@
 github.com/BurntSushi/toml v0.3.1 h1:WXkYYl6Yr3qBf1K79EBnL4mak0OimBfB0XUf9Vl28OQ=
 github.com/BurntSushi/toml v0.3.1/go.mod h1:xHWCNGjB5oqiDr8zfno3MHue2Ht5sIBksp03qcyfWMU=
-github.com/gomarkdown/markdown v0.0.0-20190912180731-281270bc6d83 h1:w5VNUHB0SP2tr1+boQJWKvnyn3P61UFErZ2e2ih6x0A=
-github.com/gomarkdown/markdown v0.0.0-20190912180731-281270bc6d83/go.mod h1:aii0r/K0ZnHv7G0KF7xy1v0A7s2Ljrb5byB7MO5p6TU=
+github.com/gomarkdown/markdown v0.0.0-20191229055418-359dc4b9d66b h1:ZodsBXcms+0AapIcegMJ4zfcAzjqUbA50YWhYq8M48w=
+github.com/gomarkdown/markdown v0.0.0-20191229055418-359dc4b9d66b/go.mod h1:aii0r/K0ZnHv7G0KF7xy1v0A7s2Ljrb5byB7MO5p6TU=
 github.com/google/go-cmp v0.2.0 h1:+dTQ8DZQJz0Mb/HjFlkptS1FeQ4cWSnN941F8aEG4SQ=
 github.com/google/go-cmp v0.2.0/go.mod h1:oXzfMopK8JAjlY9xF4vHSVASa0yLyX7SntLO5aqRK0M=
 golang.org/dl v0.0.0-20190829154251-82a15e2f2ead/go.mod h1:IUMfjQLJQd4UTqG1Z90tenwKoCX93Gn3MAQJMOSBsDQ=
diff --git a/lang/lang.go b/lang/lang.go
index 3c9a5a6..c0f29ce 100644
--- a/lang/lang.go
+++ b/lang/lang.go
@@ -11,32 +11,32 @@ func New(language string) Lang {
 	// Add all lanaguages here, the keys should be named according to BCP47.
 	// The keys must be in all lower case for normalized lookup.
 	l.m = map[string]Term{
-		"en": Term{
+		"en": {
 			Footnotes:    "Footnotes",
 			Bibliography: "Bibliography",
 			Index:        "Index",
 		},
-		"nl": Term{
+		"nl": {
 			Footnotes:    "Voetnoten",
 			Bibliography: "Bibliografie",
 			Index:        "Index",
 		},
-		"de": Term{
+		"de": {
 			Footnotes:    "Fußnoten",
 			Bibliography: "Literaturverzeichnis",
 			Index:        "Index",
 		},
-		"ja": Term{
+		"ja": {
 			Footnotes:    "脚注",
 			Bibliography: "参考文献",
 			Index:        "索引",
 		},
-		"zh-cn": Term{
+		"zh-cn": {
 			Footnotes:    "注释",
 			Bibliography: "参考文献",
 			Index:        "索引",
 		},
-		"zh-tw": Term{
+		"zh-tw": {
 			Footnotes:    "註釋",
 			Bibliography: "參考文獻",
 			Index:        "索引",
diff --git a/mast/bibliography.go b/mast/bibliography.go
index 9f1167b..3aaac74 100644
--- a/mast/bibliography.go
+++ b/mast/bibliography.go
@@ -1,8 +1,9 @@
 package mast
 
 import (
-	"github.com/gomarkdown/markdown/ast"
 	"github.com/mmarkdown/mmark/mast/reference"
+
+	"github.com/gomarkdown/markdown/ast"
 )
 
 // Bibliography represents markdown bibliography node.
diff --git a/mast/nodes.go b/mast/nodes.go
index 24ad989..b891be2 100644
--- a/mast/nodes.go
+++ b/mast/nodes.go
@@ -155,7 +155,7 @@ func AttributeFilter(node ast.Node, filter func(key string) bool) {
 	if !filter("class") {
 		a.Classes = nil
 	}
-	for k, _ := range a.Attrs {
+	for k := range a.Attrs {
 		if !filter(k) {
 			delete(a.Attrs, k)
 		}
diff --git a/mmark.go b/mmark.go
index 994dd89..d191a58 100644
--- a/mmark.go
+++ b/mmark.go
@@ -7,10 +7,6 @@ import (
 	"log"
 	"os"
 
-	"github.com/gomarkdown/markdown"
-	"github.com/gomarkdown/markdown/ast"
-	"github.com/gomarkdown/markdown/html"
-	"github.com/gomarkdown/markdown/parser"
 	"github.com/mmarkdown/mmark/lang"
 	"github.com/mmarkdown/mmark/mast"
 	"github.com/mmarkdown/mmark/mparser"
@@ -18,6 +14,11 @@ import (
 	mmarkout "github.com/mmarkdown/mmark/render/markdown"
 	"github.com/mmarkdown/mmark/render/mhtml"
 	"github.com/mmarkdown/mmark/render/xml"
+
+	"github.com/gomarkdown/markdown"
+	"github.com/gomarkdown/markdown/ast"
+	"github.com/gomarkdown/markdown/html"
+	"github.com/gomarkdown/markdown/parser"
 )
 
 var (
diff --git a/mmark_man_test.go b/mmark_man_test.go
index a343d7a..d23661f 100644
--- a/mmark_man_test.go
+++ b/mmark_man_test.go
@@ -6,11 +6,11 @@ import (
 	"path/filepath"
 	"testing"
 
-	"github.com/gomarkdown/markdown"
-	"github.com/gomarkdown/markdown/parser"
 	"github.com/mmarkdown/mmark/mparser"
 	"github.com/mmarkdown/mmark/render/man"
 
+	"github.com/gomarkdown/markdown"
+	"github.com/gomarkdown/markdown/parser"
 	"github.com/google/go-cmp/cmp"
 )
 
diff --git a/mmark_markdown_test.go b/mmark_markdown_test.go
index f5311be..2adbcbd 100644
--- a/mmark_markdown_test.go
+++ b/mmark_markdown_test.go
@@ -6,11 +6,12 @@ import (
 	"path/filepath"
 	"testing"
 
+	"github.com/mmarkdown/mmark/mparser"
+	mmarkdown "github.com/mmarkdown/mmark/render/markdown"
+
 	"github.com/gomarkdown/markdown"
 	"github.com/gomarkdown/markdown/parser"
 	"github.com/google/go-cmp/cmp"
-	"github.com/mmarkdown/mmark/mparser"
-	mmarkdown "github.com/mmarkdown/mmark/render/markdown"
 )
 
 func TestMmarkMarkdown(t *testing.T) {
diff --git a/mmark_test.go b/mmark_test.go
index 43e1a95..69d5054 100644
--- a/mmark_test.go
+++ b/mmark_test.go
@@ -6,10 +6,11 @@ import (
 	"path/filepath"
 	"testing"
 
-	"github.com/gomarkdown/markdown"
-	"github.com/gomarkdown/markdown/parser"
 	"github.com/mmarkdown/mmark/mparser"
 	"github.com/mmarkdown/mmark/render/xml"
+
+	"github.com/gomarkdown/markdown"
+	"github.com/gomarkdown/markdown/parser"
 )
 
 func TestMmarkXML(t *testing.T) {
diff --git a/render/markdown/helpers.go b/render/markdown/helpers.go
index c847d8e..0603955 100644
--- a/render/markdown/helpers.go
+++ b/render/markdown/helpers.go
@@ -6,8 +6,9 @@ import (
 	"regexp"
 	"unicode"
 
-	"github.com/gomarkdown/markdown/ast"
 	"github.com/mmarkdown/mmark/internal/text"
+
+	"github.com/gomarkdown/markdown/ast"
 )
 
 func (r *Renderer) outOneOf(w io.Writer, outFirst bool, first, second string) {
diff --git a/render/markdown/renderer.go b/render/markdown/renderer.go
index 3006082..8730453 100644
--- a/render/markdown/renderer.go
+++ b/render/markdown/renderer.go
@@ -9,9 +9,10 @@ import (
 	"strconv"
 	"strings"
 
+	"github.com/mmarkdown/mmark/mast"
+
 	"github.com/gomarkdown/markdown/ast"
 	"github.com/gomarkdown/markdown/html"
-	"github.com/mmarkdown/mmark/mast"
 )
 
 // Flags control optional behavior of Markdown renderer.
diff --git a/render/xml/bibliography.go b/render/xml/bibliography.go
index 20e495d..d59007e 100644
--- a/render/xml/bibliography.go
+++ b/render/xml/bibliography.go
@@ -6,8 +6,9 @@ import (
 	"fmt"
 	"io"
 
-	"github.com/gomarkdown/markdown/ast"
 	"github.com/mmarkdown/mmark/mast"
+
+	"github.com/gomarkdown/markdown/ast"
 )
 
 func (r *Renderer) bibliography(w io.Writer, node *mast.Bibliography, entering bool) {
diff --git a/render/xml/helpers.go b/render/xml/helpers.go
index 6bb48aa..7f7c5d0 100644
--- a/render/xml/helpers.go
+++ b/render/xml/helpers.go
@@ -6,9 +6,10 @@ import (
 	"io"
 	"strings"
 
+	"github.com/mmarkdown/mmark/mast"
+
 	"github.com/gomarkdown/markdown/ast"
 	"github.com/gomarkdown/markdown/html"
-	"github.com/mmarkdown/mmark/mast"
 )
 
 func (r *Renderer) out(w io.Writer, d []byte)  { w.Write(d) }
diff --git a/render/xml/title.go b/render/xml/title.go
index 8916a4f..c75a957 100644
--- a/render/xml/title.go
+++ b/render/xml/title.go
@@ -9,6 +9,7 @@ import (
 
 	"github.com/gomarkdown/markdown/ast"
 	"github.com/gomarkdown/markdown/html"
+
 	"github.com/mmarkdown/mmark/mast"
 )
 
diff --git a/version.go b/version.go
index 9e3a3c6..07d935d 100644
--- a/version.go
+++ b/version.go
@@ -1,4 +1,4 @@
 package main
 
 // Version of mmark.
-var Version = "2.2.0"
+var Version = "2.2.1"