diff --git a/cookie.go b/cookie.go
index 8703803..3dc1f2c 100644
--- a/cookie.go
+++ b/cookie.go
@@ -7,8 +7,10 @@ import (
 func appendCookieBytes(dst []byte, cookies []argsKV) []byte {
 	for i, n := 0, len(cookies); i < n; i++ {
 		kv := &cookies[i]
-		dst = appendQuotedArg(dst, kv.key)
-		dst = append(dst, '=')
+		if len(kv.key) > 0 {
+			dst = appendQuotedArg(dst, kv.key)
+			dst = append(dst, '=')
+		}
 		dst = appendQuotedArg(dst, kv.value)
 		if i+1 < n {
 			dst = append(dst, ';', ' ')
diff --git a/cookie_test.go b/cookie_test.go
index 00c1306..12bec57 100644
--- a/cookie_test.go
+++ b/cookie_test.go
@@ -8,11 +8,11 @@ import (
 func TestParseCookies(t *testing.T) {
 	testParseCookies(t, "", "")
 	testParseCookies(t, "=", "")
-	testParseCookies(t, "foo", "=foo")
-	testParseCookies(t, "=foo", "=foo")
+	testParseCookies(t, "foo", "foo")
+	testParseCookies(t, "=foo", "foo")
 	testParseCookies(t, "bar=", "bar=")
-	testParseCookies(t, "xxx=aa;bb=c; d; ;;e=g", "xxx=aa; bb=c; =d; e=g")
-	testParseCookies(t, "a;b;c; d=1;d=2", "=c; d=2")
+	testParseCookies(t, "xxx=aa;bb=c; =d; ;;e=g", "xxx=aa; bb=c; d; e=g")
+	testParseCookies(t, "a;b;c; d=1;d=2", "c; d=2")
 	testParseCookies(t, "   %D0%B8%D0%B2%D0%B5%D1%82=a%20b%3Bc   ;s%20s=aaa  ", "%D0%B8%D0%B2%D0%B5%D1%82=a%20b%3Bc; s%20s=aaa")
 }
 
@@ -26,9 +26,9 @@ func testParseCookies(t *testing.T, s, expectedS string) {
 }
 
 func TestAppendCookieBytes(t *testing.T) {
-	testAppendCookieBytes(t, "=", "=")
+	testAppendCookieBytes(t, "=", "")
 	testAppendCookieBytes(t, "foo=", "foo=")
-	testAppendCookieBytes(t, "=bar", "=bar")
+	testAppendCookieBytes(t, "=bar", "bar")
 	testAppendCookieBytes(t, "привет=a b;c&s s=aaa", "%D0%BF%D1%80%D0%B8%D0%B2%D0%B5%D1%82=a%20b%3Bc; s%20s=aaa")
 }