diff --git a/isvalid_test.go b/isvalid_test.go
index d61841c..b39d571 100644
--- a/isvalid_test.go
+++ b/isvalid_test.go
@@ -7,6 +7,8 @@ import (
 
 func TestXmlCheckIsValid(t *testing.T) {
 	fmt.Println("================== TestXmlCheckIsValid")
+	XmlCheckIsValid()
+	defer XmlCheckIsValid()
 
 	data := []byte(`{"":"empty", "$invalid":"hex$", "entities":"<>&", "nil": null}`)
 	m, err := NewMapJson(data)
@@ -14,13 +16,48 @@ func TestXmlCheckIsValid(t *testing.T) {
 		t.Fatal("NewMapJson err;", err)
 	}
 	fmt.Printf("%v\n", m)
+	if _, err = m.Xml(); err == nil {
+		t.Fatal("Xml err: nil")
+	}
+	if _, err = m.XmlIndent("", "   "); err == nil {
+		t.Fatal("XmlIndent err: nil")
+	}
 
-	XmlCheckIsValid()
-	defer XmlCheckIsValid()
+	data = []byte(`{"$invalid":"hex$", "entities":"<>&", "nil": null}`)
+	m, err = NewMapJson(data)
+	if err != nil {
+		t.Fatal("NewMapJson err;", err)
+	}
+	fmt.Printf("%v\n", m)
 	if _, err = m.Xml(); err == nil {
 		t.Fatal("Xml err: nil")
 	}
+	if _, err = m.XmlIndent("", "   "); err == nil {
+		t.Fatal("XmlIndent err: nil")
+	}
 
+	data = []byte(`{"entities":"<>&", "nil": null}`)
+	m, err = NewMapJson(data)
+	if err != nil {
+		t.Fatal("NewMapJson err;", err)
+	}
+	fmt.Printf("%v\n", m)
+	if _, err = m.Xml(); err == nil {
+		t.Fatal("Xml err: nil")
+	}
+	if _, err = m.XmlIndent("", "   "); err == nil {
+		t.Fatal("XmlIndent err: nil")
+	}
+
+	data = []byte(`{"nil": null}`)
+	m, err = NewMapJson(data)
+	if err != nil {
+		t.Fatal("NewMapJson err;", err)
+	}
+	fmt.Printf("%v\n", m)
+	if _, err = m.Xml(); err == nil {
+		t.Fatal("Xml err: nil")
+	}
 	if _, err = m.XmlIndent("", "   "); err == nil {
 		t.Fatal("XmlIndent err: nil")
 	}
diff --git a/xml.go b/xml.go
index 04788fd..8689a41 100644
--- a/xml.go
+++ b/xml.go
@@ -695,7 +695,7 @@ func (mv Map) Xml(rootTag ...string) ([]byte, error) {
 done:
 	if xmlCheckIsValid {
 		d := xml.NewDecoder(bytes.NewReader(b.Bytes()))
-		for _, err = d.Token(); err != io.EOF; {
+		for {
 			_, err = d.Token()
 			if err == io.EOF {
 				err = nil
@@ -945,7 +945,7 @@ func (mv Map) XmlIndent(prefix, indent string, rootTag ...string) ([]byte, error
 	}
 	if xmlCheckIsValid {
 		d := xml.NewDecoder(bytes.NewReader(b.Bytes()))
-		for _, err = d.Token(); err != io.EOF; {
+		for {
 			_, err = d.Token()
 			if err == io.EOF {
 				err = nil
diff --git a/xmlseq.go b/xmlseq.go
index 3fb90b8..80632bd 100644
--- a/xmlseq.go
+++ b/xmlseq.go
@@ -449,7 +449,7 @@ func (mv MapSeq) Xml(rootTag ...string) ([]byte, error) {
 done:
 	if xmlCheckIsValid {
 		d := xml.NewDecoder(bytes.NewReader([]byte(*s)))
-		for _, err = d.Token(); err != io.EOF; {
+		for {
 			_, err = d.Token()
 			if err == io.EOF {
 				err = nil
@@ -552,7 +552,7 @@ func (mv MapSeq) XmlIndent(prefix, indent string, rootTag ...string) ([]byte, er
 			return nil, err
 		}
 		d := xml.NewDecoder(bytes.NewReader([]byte(*s)))
-		for _, err = d.Token(); err != io.EOF; {
+		for {
 			_, err = d.Token()
 			if err == io.EOF {
 				err = nil