diff --git a/header.go b/header.go
index 7c9cc321aa..2680de5808 100644
--- a/header.go
+++ b/header.go
@@ -1804,37 +1804,6 @@ func (h *RequestHeader) parseFirstLine(buf []byte) (int, error) {
 	return len(buf) - len(bNext), nil
 }
 
-func peekRawHeader(buf, key []byte) []byte {
-	n := bytes.Index(buf, key)
-	if n < 0 {
-		return nil
-	}
-	if n > 0 && buf[n-1] != nChar {
-		return nil
-	}
-	n += len(key)
-	if n >= len(buf) {
-		return nil
-	}
-	if buf[n] != ':' {
-		return nil
-	}
-	n++
-	if buf[n] != ' ' {
-		return nil
-	}
-	n++
-	buf = buf[n:]
-	n = bytes.IndexByte(buf, nChar)
-	if n < 0 {
-		return nil
-	}
-	if n > 0 && buf[n-1] == rChar {
-		n--
-	}
-	return buf[:n]
-}
-
 func readRawHeaders(dst, buf []byte) ([]byte, int, error) {
 	n := bytes.IndexByte(buf, nChar)
 	if n < 0 {
diff --git a/header_test.go b/header_test.go
index 0f7c7f8f85..354ebb4866 100644
--- a/header_test.go
+++ b/header_test.go
@@ -1054,35 +1054,6 @@ func TestRequestHeaderProxyWithCookie(t *testing.T) {
 	}
 }
 
-func TestPeekRawHeader(t *testing.T) {
-	t.Parallel()
-
-	// empty header
-	testPeekRawHeader(t, "", "Foo-Bar", "")
-
-	// different case
-	testPeekRawHeader(t, "Content-Length: 3443\r\n", "content-length", "")
-
-	// no trailing crlf
-	testPeekRawHeader(t, "Content-Length: 234", "Content-Length", "")
-
-	// single header
-	testPeekRawHeader(t, "Content-Length: 12345\r\n", "Content-Length", "12345")
-
-	// multiple headers
-	testPeekRawHeader(t, "Host: foobar\r\nContent-Length: 434\r\nFoo: bar\r\n\r\n", "Content-Length", "434")
-
-	// lf without cr
-	testPeekRawHeader(t, "Foo: bar\nConnection: close\nAaa: bbb\ncc: ddd\n", "Connection", "close")
-}
-
-func testPeekRawHeader(t *testing.T, rawHeaders, key string, 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 TestResponseHeaderFirstByteReadEOF(t *testing.T) {
 	t.Parallel()