diff --git a/docs/megolm.md b/docs/megolm.md
index f9acfd0..b9eedec 100644
--- a/docs/megolm.md
+++ b/docs/megolm.md
@@ -76,7 +76,7 @@ from $`R_{i,0}`$.
 
 The complete ratchet value, $`R_{i}`$, is hashed to generate the keys used
 to encrypt each message. This scheme allows the ratchet to be advanced an
-arbitrary amount forwards while needing at most 1023 hash computations.  A
+arbitrary amount forwards while needing at most 1020 hash computations.  A
 client can decrypt chat history onwards from the earliest value of the ratchet
 it is aware of, but cannot decrypt history from before that point without
 reversing the hash function.