diff --git a/header.go b/header.go
index 66d2be4..dae683a 100644
--- a/header.go
+++ b/header.go
@@ -63,38 +63,34 @@ type RequestHeader struct {
 
 // ConnectionClose returns true if 'Connection: close' header is set.
 func (h *ResponseHeader) ConnectionClose() bool {
-	if !h.rawHeadersParsed {
-		if h.ContentLength() == -2 {
-			return true
-		}
-		if bytes.Equal(peekRawHeader(h.rawHeaders, strConnection), strClose) {
-			return true
-		}
-		// h.parseRawHeaders() isn't called for performance reasons.
-	}
+	h.parseRawHeaders()
 	return h.connectionClose
 }
 
 // SetConnectionClose sets 'Connection: close' header.
 func (h *ResponseHeader) SetConnectionClose() {
-	h.parseRawHeaders()
+	// h.parseRawHeaders() isn't called for performance reasons.
 	h.connectionClose = true
 }
 
 // ConnectionClose returns true if 'Connection: close' header is set.
 func (h *RequestHeader) ConnectionClose() bool {
+	// h.parseRawHeaders() isn't called for performance reasons.
 	if !h.rawHeadersParsed {
-		if bytes.Equal(peekRawHeader(h.rawHeaders, strConnection), strClose) {
+		if h.connectionClose {
+			return true
+		}
+		if hasRawHeader(h.rawHeaders, strConnectionClose) {
+			h.connectionClose = true
 			return true
 		}
-		// h.parseRawHeaders() isn't called for performance reasons.
 	}
 	return h.connectionClose
 }
 
 // SetConnectionClose sets 'Connection: close' header.
 func (h *RequestHeader) SetConnectionClose() {
-	h.parseRawHeaders()
+	// h.parseRawHeaders() isn't called for performance reasons.
 	h.connectionClose = true
 }
 
@@ -104,28 +100,7 @@ func (h *RequestHeader) SetConnectionClose() {
 // -1 means Transfer-Encoding: chunked.
 // -2 means Transfer-Encoding: identity.
 func (h *ResponseHeader) ContentLength() int {
-	if !h.rawHeadersParsed {
-		if h.contentLength < 0 || len(h.contentLengthBytes) > 0 {
-			return h.contentLength
-		}
-		value := peekRawHeader(h.rawHeaders, strTransferEncoding)
-		if len(value) > 0 {
-			if bytes.Equal(value, strIdentity) {
-				h.connectionClose = true
-				h.contentLength = -2
-				return h.contentLength
-			}
-			h.contentLength = -1
-			return h.contentLength
-		}
-		value = peekRawHeader(h.rawHeaders, strContentLength)
-		if contentLength, err := parseContentLength(value); err == nil {
-			h.contentLength = contentLength
-			h.contentLengthBytes = append(h.contentLengthBytes[:0], value...)
-			return contentLength
-		}
-		h.parseRawHeaders()
-	}
+	h.parseRawHeaders()
 	return h.contentLength
 }
 
@@ -156,62 +131,13 @@ func (h *ResponseHeader) SetContentLength(contentLength int) {
 // It may be negative:
 // -1 means Transfer-Encoding: chunked.
 func (h *RequestHeader) ContentLength() int {
-	if h.IsGet() || h.IsHead() {
+	if !h.IsPost() {
 		return 0
 	}
-	if !h.rawHeadersParsed {
-		if h.contentLength < 0 || len(h.contentLengthBytes) > 0 {
-			return h.contentLength
-		}
-		value := peekRawHeader(h.rawHeaders, strTransferEncoding)
-		if len(value) > 0 {
-			h.contentLength = -1
-			return h.contentLength
-		}
-		value = peekRawHeader(h.rawHeaders, strContentLength)
-		if contentLength, err := parseContentLength(value); err == nil {
-			h.contentLength = contentLength
-			h.contentLengthBytes = append(h.contentLengthBytes[:0], value...)
-			return contentLength
-		}
-		h.parseRawHeaders()
-	}
+	h.parseRawHeaders()
 	return h.contentLength
 }
 
-func peekRawHeader(buf, key []byte) []byte {
-	n := bytes.Index(buf, key)
-	if n < 0 {
-		return nil
-	}
-	if n > 0 && buf[n-1] != '\n' {
-		return nil
-	}
-	buf = buf[n+len(key):]
-	if len(buf) == 0 {
-		return nil
-	}
-	if buf[0] != ':' {
-		return nil
-	}
-	n = 1
-	for len(buf) > n && buf[n] == ' ' {
-		n++
-	}
-	buf = buf[n:]
-	n = bytes.IndexByte(buf, '\n')
-	if n < 0 {
-		return nil
-	}
-	if n > 0 && buf[n-1] == '\r' {
-		n--
-	}
-	for n > 0 && buf[n-1] == ' ' {
-		n--
-	}
-	return buf[:n]
-}
-
 // SetContentLength sets Content-Length header value.
 //
 // Negative content-length sets 'Transfer-Encoding: chunked' header.
@@ -1076,6 +1002,7 @@ func (h *ResponseHeader) parse(buf []byte) (int, error) {
 		return 0, err
 	}
 	h.rawHeaders = rawHeaders
+
 	return m + n, nil
 }
 
@@ -1089,6 +1016,7 @@ func (h *RequestHeader) parse(buf []byte) (int, error) {
 		return 0, err
 	}
 	h.rawHeaders = rawHeaders
+
 	return m + n, nil
 }
 
@@ -1160,6 +1088,28 @@ func (h *RequestHeader) parseFirstLine(buf []byte) (int, error) {
 	return len(buf) - len(bNext), nil
 }
 
+func hasRawHeader(buf, s []byte) bool {
+	n := bytes.Index(buf, s)
+	if n < 0 {
+		return false
+	}
+	if n > 0 && buf[n-1] != '\n' {
+		return false
+	}
+	n += len(s)
+	if n >= len(buf) {
+		return false
+	}
+	switch buf[n] {
+	case '\r':
+		return len(buf) > n+1 && buf[n+1] == '\n'
+	case '\n':
+		return true
+	default:
+		return false
+	}
+}
+
 func readRawHeaders(dst, buf []byte) ([]byte, int, error) {
 	dst = dst[:0]
 	n := bytes.IndexByte(buf, '\n')
diff --git a/header_test.go b/header_test.go
index 5381119..efc9de6 100644
--- a/header_test.go
+++ b/header_test.go
@@ -10,30 +10,30 @@ import (
 	"testing"
 )
 
-func TestPeekRawHeader(t *testing.T) {
+func TestHasRawHeader(t *testing.T) {
 	// empty header
-	testPeekRawHeader(t, "", "Foo-Bar", "")
+	testHasRawHeader(t, "", "Foo-Bar", false)
 
 	// different case
-	testPeekRawHeader(t, "Content-Length: 3443\r\n", "content-length", "")
+	testHasRawHeader(t, "Content-Length: 3443\r\n", "content-length: 3443", false)
 
 	// no trailing crlf
-	testPeekRawHeader(t, "Content-Length: 234", "Content-Length", "")
+	testHasRawHeader(t, "Content-Length: 234", "Content-Length: 234", false)
 
 	// single header
-	testPeekRawHeader(t, "Content-Length: 12345\r\n", "Content-Length", "12345")
+	testHasRawHeader(t, "Content-Length: 12345\r\n", "Content-Length: 12345", true)
 
 	// multiple headers
-	testPeekRawHeader(t, "Host: foobar\r\nContent-Length: 434\r\nFoo: bar\r\n\r\n", "Content-Length", "434")
+	testHasRawHeader(t, "Host: foobar\r\nContent-Length: 434\r\nFoo: bar\r\n\r\n", "Content-Length: 434", true)
 
 	// lf without cr
-	testPeekRawHeader(t, "Foo: bar\nConnection: close\nAaa: bbb\ncc: ddd\n", "Connection", "close")
+	testHasRawHeader(t, "Foo: bar\nConnection: close\nAaa: bbb\ncc: ddd\n", "Connection: close", true)
 }
 
-func testPeekRawHeader(t *testing.T, rawHeaders, key, expectedValue string) {
-	v := peekRawHeader([]byte(rawHeaders), []byte(key))
-	if string(v) != expectedValue {
-		t.Fatalf("unexpected raw headers value %q. Expected %q. key %q, rawHeaders %q", v, expectedValue, key, rawHeaders)
+func testHasRawHeader(t *testing.T, rawHeaders, s string, expectedValue bool) {
+	v := hasRawHeader([]byte(rawHeaders), []byte(s))
+	if v != expectedValue {
+		t.Fatalf("unexpected raw headers value %v. Expected %v. s %q, rawHeaders %q", v, expectedValue, s, rawHeaders)
 	}
 }
 
@@ -811,7 +811,7 @@ func TestResponseHeaderReadSuccess(t *testing.T) {
 
 	// duplicate content-length
 	testResponseHeaderReadSuccess(t, h, "HTTP/1.1 200 OK\r\nContent-Length: 456\r\nContent-Type: foo/bar\r\nContent-Length: 321\r\n\r\n",
-		200, 456, "foo/bar", "")
+		200, 321, "foo/bar", "")
 
 	// duplicate content-type
 	testResponseHeaderReadSuccess(t, h, "HTTP/1.1 200 OK\r\nContent-Length: 234\r\nContent-Type: foo/bar\r\nContent-Type: baz/bar\r\n\r\n",
@@ -936,7 +936,7 @@ func TestRequestHeaderReadSuccess(t *testing.T) {
 
 	// post with duplicate content-length
 	testRequestHeaderReadSuccess(t, h, "POST /xx HTTP/1.1\r\nHost: aa\r\nContent-Type: s\r\nContent-Length: 13\r\nContent-Length: 1\r\n\r\n",
-		13, "/xx", "aa", "", "s", "")
+		1, "/xx", "aa", "", "s", "")
 
 	// non-post with content-type
 	testRequestHeaderReadSuccess(t, h, "GET /aaa HTTP/1.1\r\nHost: bbb.com\r\nContent-Type: aaab\r\n\r\n",
diff --git a/strings.go b/strings.go
index bf8f10e..70bd9d9 100644
--- a/strings.go
+++ b/strings.go
@@ -23,6 +23,7 @@ var (
 	strPost = []byte("POST")
 
 	strConnection       = []byte("Connection")
+	strConnectionClose  = []byte("Connection: close")
 	strContentLength    = []byte("Content-Length")
 	strContentType      = []byte("Content-Type")
 	strDate             = []byte("Date")