diff --git a/pkg/ueps/packet_test.go b/pkg/ueps/packet_test.go
index 35eb133..c6b8751 100644
--- a/pkg/ueps/packet_test.go
+++ b/pkg/ueps/packet_test.go
@@ -116,9 +116,8 @@ func TestPacket_MarshalAndSign_Bad(t *testing.T) {
 	}
 }
 
-// the HMAC stored in the frame (the frame is immutable once signed).
 // frame, _ := builder.MarshalAndSign(secret)
-// // modifying frame[len(frame)-1] breaks HMAC verification
+// corrupted[len(frame)-1] ^= 0xFF // modifying any byte breaks HMAC verification
 func TestPacket_MarshalAndSign_Ugly(t *testing.T) {
 	builder := NewBuilder(0x03, []byte("sensitive"))
 	sharedSecret := []byte("my-secret")