diff --git a/book/source/08-signing_components.md b/book/source/08-signing_components.md
index cd1aa1b..ee336be 100644
--- a/book/source/08-signing_components.md
+++ b/book/source/08-signing_components.md
@@ -377,7 +377,7 @@ The structure of such a signature is straightforward:
 | Reason for Revocation   | Hashed | True           | False             | Determines soft or hard revocation             |
 
 
-In `SubkeyRevocation` signatures, the [reason for revocation](https://www.ietf.org/archive/id/draft-ietf-openpgp-crypto-refresh-12.html#name-reason-for-revocation) subpacket is critical. The values `1` (key superseded) and `3` (key retired and no longer used) indicate soft revocations, whereas values `0` (no  reason) and `2` (key compromised) indicate hard revocations. 
+In `SubkeyRevocation` signatures, the [reason for revocation](https://www.ietf.org/archive/id/draft-ietf-openpgp-crypto-refresh-12.html#name-reason-for-revocation) subpacket can only have values in the range of `0-3`. The values `1` (key superseded) and `3` (key retired and no longer used) indicate soft revocations, whereas values `0` (no reason) and `2` (key compromised) indicate hard revocations. 
 
 Note that a value of `32` is not applicable in these signatures.