diff --git a/main_test.go b/main_test.go
index 63140ea..955e520 100644
--- a/main_test.go
+++ b/main_test.go
@@ -6,6 +6,42 @@ import (
 	"github.com/stretchr/testify/assert"
 )
 
+func TestHasSyncWord(t *testing.T) {
+	testCases := []struct {
+		name      string
+		bytes     []byte
+		expResult bool
+	}{
+		{
+			"empty header",
+			[]byte{0, 0, 0, 0},
+			false,
+		},
+		{
+			"almost",
+			[]byte{0xff, 0xc0, 0, 0},
+			false,
+		},
+		{
+			"present",
+			[]byte{0xff, 0xe0, 0, 0},
+			true,
+		},
+		{
+			"full header",
+			[]byte{0xff, 0xff, 0xff, 0xff},
+			true,
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			h := header(tc.bytes)
+			assert.Equal(t, tc.expResult, h.HasSyncWord())
+		})
+	}
+}
+
 func TestAudioVersionId(t *testing.T) {
 	bytes := []byte{0xff, 0xe8, 0, 0}
 	h := header(bytes)