Blake2b empty messages may be NULL

diff --git a/doc/man/man3/crypto_blake2b.3monocypher b/doc/man/man3/crypto_blake2b.3monocypher
index fb44b98a56d0ec1d15dac83a349f9a4f2f53f3e7..60eaf747515c7b26d1a589cec00de7cf3af6ed32 100644 (file)
--- a/doc/man/man3/crypto_blake2b.3monocypher
+++ b/doc/man/man3/crypto_blake2b.3monocypher
@@ -96,6 +96,11 @@ Must be between 0 and 64.
 The message to hash.
 May overlap with
 .Fa hash .
+May be
+.Dv NULL
+if
+.Fa message_size
+is 0.
 .It Fa message_size
 Length of
 .Fa message ,