diff --git a/client.go b/client.go
index cdab4432..49a24a96 100644
--- a/client.go
+++ b/client.go
@@ -46,27 +46,9 @@ type Client struct {
 //	co.Close()
 //
 func Exchange(m *Msg, a string) (r *Msg, err error) {
-	var co *Conn
-	co, err = DialTimeout("udp", a, dnsTimeout)
-	if err != nil {
-		return nil, err
-	}
-
-	defer co.Close()
-	co.SetReadDeadline(time.Now().Add(dnsTimeout))
-	co.SetWriteDeadline(time.Now().Add(dnsTimeout))
-
-	opt := m.IsEdns0()
-	// If EDNS0 is used use that for size.
-	if opt != nil && opt.UDPSize() >= MinMsgSize {
-		co.UDPSize = opt.UDPSize()
-	}
-
-	if err = co.WriteMsg(m); err != nil {
-		return nil, err
-	}
-	r, err = co.ReadMsg()
-	return r, err
+	c := Client{}
+	r, _, err = c.Exchange(m, a)
+	return
 }
 
 // ExchangeConn performs a synchronous query. It sends the message m via the connection
@@ -86,6 +68,9 @@ func ExchangeConn(c net.Conn, m *Msg) (r *Msg, err error) {
 		return nil, err
 	}
 	r, err = co.ReadMsg()
+	if err == nil && r.Id != m.Id {
+		err = ErrId
+	}
 	return r, err
 }
 
@@ -161,6 +146,9 @@ func (c *Client) exchange(m *Msg, a string) (r *Msg, rtt time.Duration, err erro
 		return nil, 0, err
 	}
 	r, err = co.ReadMsg()
+	if err == nil && r.Id != m.Id {
+		err = ErrId
+	}
 	return r, co.rtt, err
 }
 
diff --git a/client_test.go b/client_test.go
index d0294f97..8a70c7ea 100644
--- a/client_test.go
+++ b/client_test.go
@@ -37,6 +37,29 @@ func TestClientSync(t *testing.T) {
 	}
 }
 
+func TestClientSyncBadId(t *testing.T) {
+	HandleFunc("miek.nl.", HelloServerBadId)
+	defer HandleRemove("miek.nl.")
+
+	s, addrstr, err := RunLocalUDPServer("127.0.0.1:0")
+	if err != nil {
+		t.Fatalf("Unable to run test server: %v", err)
+	}
+	defer s.Shutdown()
+
+	m := new(Msg)
+	m.SetQuestion("miek.nl.", TypeSOA)
+
+	c := new(Client)
+	if _, _, err := c.Exchange(m, addrstr); err != ErrId {
+		t.Errorf("did not find a bad Id")
+	}
+	// And now with plain Exchange().
+	if _, err := Exchange(m, addrstr); err != ErrId {
+		t.Errorf("did not find a bad Id")
+	}
+}
+
 func TestClientEDNS0(t *testing.T) {
 	HandleFunc("miek.nl.", HelloServer)
 	defer HandleRemove("miek.nl.")
diff --git a/server_test.go b/server_test.go
index c2422b1f..dff0fb52 100644
--- a/server_test.go
+++ b/server_test.go
@@ -17,6 +17,16 @@ func HelloServer(w ResponseWriter, req *Msg) {
 	w.WriteMsg(m)
 }
 
+func HelloServerBadId(w ResponseWriter, req *Msg) {
+	m := new(Msg)
+	m.SetReply(req)
+	m.Id += 1
+
+	m.Extra = make([]RR, 1)
+	m.Extra[0] = &TXT{Hdr: RR_Header{Name: m.Question[0].Name, Rrtype: TypeTXT, Class: ClassINET, Ttl: 0}, Txt: []string{"Hello world"}}
+	w.WriteMsg(m)
+}
+
 func AnotherHelloServer(w ResponseWriter, req *Msg) {
 	m := new(Msg)
 	m.SetReply(req)