diff --git a/src/net/dnsclient_unix.go b/src/net/dnsclient_unix.go
index 21aa91f665ad3d..0b29fcb6d32b5f 100644
--- a/src/net/dnsclient_unix.go
+++ b/src/net/dnsclient_unix.go
@@ -82,7 +82,7 @@ func dnsPacketRoundTrip(c Conn, id uint16, query dnsmessage.Question, b []byte)
 		return dnsmessage.Parser{}, dnsmessage.Header{}, err
 	}
 
-	b = make([]byte, 512) // see RFC 1035
+	b = make([]byte, 1232) // see RFC 6891, https://dnsflagday.net/2020/
 	for {
 		n, err := c.Read(b)
 		if err != nil {
diff --git a/src/net/dnsclient_unix_test.go b/src/net/dnsclient_unix_test.go
index 14366eca8c63b1..ed8ec9a570167c 100644
--- a/src/net/dnsclient_unix_test.go
+++ b/src/net/dnsclient_unix_test.go
@@ -881,7 +881,7 @@ func (f *fakeDNSPacketConn) Close() error {
 func TestIgnoreDNSForgeries(t *testing.T) {
 	c, s := Pipe()
 	go func() {
-		b := make([]byte, 512)
+		b := make([]byte, 1232)
 		n, err := s.Read(b)
 		if err != nil {
 			t.Error(err)