diff --git a/client.go b/client.go
index 2631e6ce..dc7016d1 100644
--- a/client.go
+++ b/client.go
@@ -278,7 +278,6 @@ func (c *Client) appendRootCertData(data []byte) {
 		config.RootCAs = x509.NewCertPool()
 	}
 	config.RootCAs.AppendCertsFromPEM(data)
-	return
 }
 
 // SetRootCertFromString set root certificates from string.
diff --git a/client_test.go b/client_test.go
index ccf62f57..b87745cb 100644
--- a/client_test.go
+++ b/client_test.go
@@ -242,10 +242,7 @@ func TestAutoDecode(t *testing.T) {
 	assertSuccess(t, resp, err)
 	tests.AssertEqual(t, "我是roc", resp.String())
 	resp, err = c.SetAutoDecodeContentTypeFunc(func(contentType string) bool {
-		if strings.Contains(contentType, "text") {
-			return true
-		}
-		return false
+		return strings.Contains(contentType, "text")
 	}).R().Get("/gbk")
 	assertSuccess(t, resp, err)
 	tests.AssertEqual(t, "我是roc", resp.String())
diff --git a/internal/altsvcutil/altsvcutil.go b/internal/altsvcutil/altsvcutil.go
index 8aa160a0..84978d7e 100644
--- a/internal/altsvcutil/altsvcutil.go
+++ b/internal/altsvcutil/altsvcutil.go
@@ -79,7 +79,6 @@ func (p *altAvcParser) Parse() (as []*altsvc.AltSvc, err error) {
 			}
 		}
 	}
-	return
 }
 
 func (p *altAvcParser) parseKv() (key, value string, haveNextField bool, err error) {
diff --git a/middleware.go b/middleware.go
index 59cd46f5..c310cd3d 100644
--- a/middleware.go
+++ b/middleware.go
@@ -256,7 +256,6 @@ func unmarshalBody(c *Client, r *Response, v interface{}) (err error) {
 		}
 		return c.jsonUnmarshal(body, v)
 	}
-	return
 }
 
 func defaultResultStateChecker(resp *Response) ResultState {
@@ -490,9 +489,9 @@ func parseRequestHeader(c *Client, r *Request) error {
 }
 
 func parseRequestCookie(c *Client, r *Request) error {
-	if len(c.Cookies) == 0 || r.RetryAttempt > 0 {
-		return nil
+	if len(c.Cookies) > 0 || r.RetryAttempt <= 0 {
+		r.Cookies = append(r.Cookies, c.Cookies...)
 	}
-	r.Cookies = append(r.Cookies, c.Cookies...)
+
 	return nil
 }
diff --git a/redirect.go b/redirect.go
index 364a55eb..f1cc4331 100644
--- a/redirect.go
+++ b/redirect.go
@@ -55,9 +55,9 @@ func SameHostRedirectPolicy() RedirectPolicy {
 // AllowedHostRedirectPolicy allows redirect only if the redirected host
 // match one of the host that specified.
 func AllowedHostRedirectPolicy(hosts ...string) RedirectPolicy {
-	m := make(map[string]bool)
+	m := make(map[string]struct{})
 	for _, h := range hosts {
-		m[strings.ToLower(getHostname(h))] = true
+		m[strings.ToLower(getHostname(h))] = struct{}{}
 	}
 
 	return func(req *http.Request, via []*http.Request) error {
@@ -72,9 +72,9 @@ func AllowedHostRedirectPolicy(hosts ...string) RedirectPolicy {
 // AllowedDomainRedirectPolicy allows redirect only if the redirected domain
 // match one of the domain that specified.
 func AllowedDomainRedirectPolicy(hosts ...string) RedirectPolicy {
-	domains := make(map[string]bool)
+	domains := make(map[string]struct{})
 	for _, h := range hosts {
-		domains[strings.ToLower(getDomain(h))] = true
+		domains[strings.ToLower(getDomain(h))] = struct{}{}
 	}
 
 	return func(req *http.Request, via []*http.Request) error {