diff --git a/PROTOCOL.md b/PROTOCOL.md
index 4733ac4..71174db 100644
--- a/PROTOCOL.md
+++ b/PROTOCOL.md
@@ -187,8 +187,8 @@ When receiving an invalid token, the server may send back to the client a challe
 
 | Step | Calculation |
 |:--------:|:------|
-| `1` | $t\_s = \mid \frac{t\_{now}}{W}\mid$ |
+| `1` | $t\_s = \mid \frac{t\_{now}}{W}\mid, m\_s = t\_s \ \mathbb{Z}\_{(2)}$ |
 | `2` | $y\_1 = T \oplus h(t\_c)$ |
-| `3` | $y\_2 = y\_1 \oplus (t\_c \ \mathbb{Z}\_{(2)})$ |
+| `3` | $y\_2 = y\_1 \oplus m\_s$ |
 
 Send $y_1$ and $y_2$.
\ No newline at end of file