diff --git a/render/render_msgpack_test.go b/render/render_msgpack_test.go
index 579897cc..48b23870 100644
--- a/render/render_msgpack_test.go
+++ b/render/render_msgpack_test.go
@@ -7,7 +7,7 @@
 package render
 
 import (
-	"bytes"
+	"errors"
 	"net/http/httptest"
 	"testing"
 
@@ -16,9 +16,6 @@ import (
 	"github.com/ugorji/go/codec"
 )
 
-// TODO unit tests
-// test errors
-
 func TestRenderMsgPack(t *testing.T) {
 	w := httptest.NewRecorder()
 	data := map[string]any{
@@ -32,13 +29,52 @@ func TestRenderMsgPack(t *testing.T) {
 
 	require.NoError(t, err)
 
-	h := new(codec.MsgpackHandle)
-	assert.NotNil(t, h)
-	buf := bytes.NewBuffer([]byte{})
-	assert.NotNil(t, buf)
-	err = codec.NewEncoder(buf, h).Encode(data)
-
+	var decoded map[string]any
+	var mh codec.MsgpackHandle
+	mh.RawToString = true
+	err = codec.NewDecoderBytes(w.Body.Bytes(), &mh).Decode(&decoded)
 	require.NoError(t, err)
-	assert.Equal(t, w.Body.String(), buf.String())
+	assert.Equal(t, data, decoded)
 	assert.Equal(t, "application/msgpack; charset=utf-8", w.Header().Get("Content-Type"))
 }
+
+func TestWriteMsgPack(t *testing.T) {
+	w := httptest.NewRecorder()
+	data := map[string]any{
+		"foo": "bar",
+		"num": 42,
+	}
+
+	err := WriteMsgPack(w, data)
+	require.NoError(t, err)
+
+	assert.Equal(t, "application/msgpack; charset=utf-8", w.Header().Get("Content-Type"))
+
+	var decoded map[string]any
+	var mh codec.MsgpackHandle
+	mh.RawToString = true
+	err = codec.NewDecoderBytes(w.Body.Bytes(), &mh).Decode(&decoded)
+	require.NoError(t, err)
+	assert.Len(t, decoded, 2)
+	assert.Equal(t, "bar", decoded["foo"])
+	assert.EqualValues(t, 42, decoded["num"])
+}
+
+type failWriter struct {
+	*httptest.ResponseRecorder
+}
+
+func (w *failWriter) Write(data []byte) (int, error) {
+	return 0, errors.New("write error")
+}
+
+func TestRenderMsgPackError(t *testing.T) {
+	w := httptest.NewRecorder()
+	data := map[string]any{
+		"foo": "bar",
+	}
+
+	err := (MsgPack{data}).Render(&failWriter{w})
+	require.Error(t, err)
+	assert.Contains(t, err.Error(), "write error")
+}