diff --git a/udp/server_libcoap_test.go b/udp/server_libcoap_test.go
index d9318ad6..738f36d7 100644
--- a/udp/server_libcoap_test.go
+++ b/udp/server_libcoap_test.go
@@ -4,12 +4,6 @@ import (
 	"bytes"
 	"errors"
 	"fmt"
-	"math/rand"
-	"os/exec"
-	"strconv"
-	"sync"
-	"testing"
-
 	"github.com/plgd-dev/go-coap/v3/message"
 	"github.com/plgd-dev/go-coap/v3/message/codes"
 	"github.com/plgd-dev/go-coap/v3/mux"
@@ -17,6 +11,11 @@ import (
 	"github.com/plgd-dev/go-coap/v3/options"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
+	"math/rand"
+	"os/exec"
+	"strconv"
+	"sync"
+	"testing"
 )
 
 func TestConnGetBlockwise(t *testing.T) {
@@ -76,7 +75,7 @@ func TestConnGetBlockwise(t *testing.T) {
 
 	err = m.Handle("/big", mux.HandlerFunc(func(w mux.ResponseWriter, r *mux.Message) {
 		assert.Equal(t, codes.GET, r.Code())
-		errS := w.SetResponse(codes.Content, message.AppOctets, bytes.NewReader([]byte(bigPayload10KiB)))
+		errS := w.SetResponse(codes.Content, message.AppOctets, bytes.NewReader(bigPayload10KiB))
 		require.NoError(t, errS)
 		require.NotEmpty(t, w.Conn())
 		require.Equal(t, message.Confirmable, r.Type())
@@ -92,7 +91,6 @@ func TestConnGetBlockwise(t *testing.T) {
 		errS := s.Serve(l)
 		assert.NoError(t, errS)
 	}()
-
 	cc, err := Dial(l.LocalAddr().String())
 	require.NoError(t, err)
 	defer func() {
@@ -233,7 +231,7 @@ func TestConnPostBlockwise(t *testing.T) {
 			wantCode:    codes.Content,
 			wantErr:     false,
 			useToken:    true,
-			wantPayload: []byte(bigPayload10KiB),
+			wantPayload: bigPayload10KiB,
 		},
 		{
 			name: "block-post-without-token",
@@ -243,7 +241,7 @@ func TestConnPostBlockwise(t *testing.T) {
 			wantCode:    codes.Content,
 			wantErr:     false,
 			useToken:    false,
-			wantPayload: []byte(bigPayload10KiB),
+			wantPayload: bigPayload10KiB,
 		},
 	}
 
@@ -267,7 +265,7 @@ func TestConnPostBlockwise(t *testing.T) {
 	err = m.Handle("/big", mux.HandlerFunc(func(w mux.ResponseWriter, r *mux.Message) {
 		assert.Equal(t, codes.POST, r.Code())
 		received, err2 := r.ReadBody()
-		errS := w.SetResponse(codes.Content, message.TextPlain, bytes.NewReader([]byte(bigPayload10KiB)))
+		errS := w.SetResponse(codes.Content, message.TextPlain, bytes.NewReader(bigPayload10KiB))
 		require.NoError(t, err2)
 		assert.Equal(t, bigPayload10KiB, received)
 		require.NoError(t, errS)
@@ -322,8 +320,7 @@ func sendCoAPRequestLibCoAP(address string, method string, path string, payload
 	var args []string
 	args = append(args, "-m", method)
 	if token {
-		rand.Uint64()
-		args = append(args, "-T", strconv.FormatUint(rand.Uint64(), 10))
+		args = append(args, "-T", strconv.FormatUint(uint64(rand.Uint32()), 16))
 	}
 	if payload {
 		args = append(args, "-b", "1024")
@@ -347,7 +344,7 @@ func sendCoAPRequestLibCoAP(address string, method string, path string, payload
 	return out.Bytes(), nil
 }
 
-const bigPayload10KiB = `89075337635954647102216077828334038179638965680796041208684221958292459041499210220101176726750119361506928946801115768179724
+var bigPayload10KiB = []byte(`89075337635954647102216077828334038179638965680796041208684221958292459041499210220101176726750119361506928946801115768179724
 42244632672758898527798766326186965189573496725417576843236332384515325066967967084729236662659424427203830789178855960389888
 59671607161000645588293584669984665020199777828148967747970527020608102921980556435899241646582421992569038754973449362160805
 31239955776017464552148435666505635723861800404618684226812752076597749931057757306056294943547000781262839809899923354086591
@@ -428,4 +425,4 @@ const bigPayload10KiB = `8907533763595464710221607782833403817963896568079604120
 91655282321189488943674583928812971734718557687261267540861951330156857260194972959320584575281425950364513866555614168110966
 87585502488315874658362449099439868192063303681917995993161431685969345689815394695246096186072665320424126902383281639806078
 13897268972795607841085430069511881664533488909312510299548807790607510574162189448464719710343594178873230685172521870698370
-6337814198009624212201025856162445`
+6337814198009624212201025856162445`)