diff --git a/extension/table.go b/extension/table.go
index f0e994e..580ca9e 100644
--- a/extension/table.go
+++ b/extension/table.go
@@ -419,7 +419,7 @@ func (r *TableHTMLRenderer) renderTableCell(w util.BufWriter, source []byte, nod
 					cob.AppendByte(';')
 				}
 				style := fmt.Sprintf("text-align:%s", n.Alignment.String())
-				cob.Append(util.StringToReadOnlyBytes(style))
+				cob.AppendString(style)
 				n.SetAttributeString("style", cob.Bytes())
 			}
 		}
diff --git a/parser/raw_html.go b/parser/raw_html.go
index d7ba414..9fd9e22 100644
--- a/parser/raw_html.go
+++ b/parser/raw_html.go
@@ -2,10 +2,11 @@ package parser
 
 import (
 	"bytes"
+	"regexp"
+
 	"github.com/yuin/goldmark/ast"
 	"github.com/yuin/goldmark/text"
 	"github.com/yuin/goldmark/util"
-	"regexp"
 )
 
 type rawHTMLParser struct {
@@ -102,7 +103,3 @@ func (s *rawHTMLParser) parseMultiLineRegexp(reg *regexp.Regexp, block text.Read
 	}
 	return nil
 }
-
-func (s *rawHTMLParser) CloseBlock(parent ast.Node, pc Context) {
-	// nothing to do
-}
diff --git a/util/util.go b/util/util.go
index fc1438d..be82394 100644
--- a/util/util.go
+++ b/util/util.go
@@ -37,6 +37,12 @@ func (b *CopyOnWriteBuffer) Write(value []byte) {
 	b.buffer = append(b.buffer, value...)
 }
 
+// WriteString writes given string to the buffer.
+// WriteString allocate new buffer and clears it at the first time.
+func (b *CopyOnWriteBuffer) WriteString(value string) {
+	b.Write(StringToReadOnlyBytes(value))
+}
+
 // Append appends given bytes to the buffer.
 // Append copy buffer at the first time.
 func (b *CopyOnWriteBuffer) Append(value []byte) {
@@ -49,6 +55,12 @@ func (b *CopyOnWriteBuffer) Append(value []byte) {
 	b.buffer = append(b.buffer, value...)
 }
 
+// AppendString appends given string to the buffer.
+// AppendString copy buffer at the first time.
+func (b *CopyOnWriteBuffer) AppendString(value string) {
+	b.Append(StringToReadOnlyBytes(value))
+}
+
 // WriteByte writes the given byte to the buffer.
 // WriteByte allocate new buffer and clears it at the first time.
 func (b *CopyOnWriteBuffer) WriteByte(c byte) {