diff --git a/readme.md b/readme.md
index 249d78c..38a54b4 100644
--- a/readme.md
+++ b/readme.md
@@ -5,7 +5,7 @@ This is a portable implementation of [Ed25519](http://ed25519.cr.yp.to/) based
 on the SUPERCOP "ref10" implementation. All code is in the public domain.
 
 All code is pure ANSI C without any dependencies, except for the random seed
-generation which uses standard OS cryptography APIs. If you wish to be entirely
+generation which uses standard OS cryptography APIs (`CryptGenRandom` on Windows, `/dev/random` on *nix). If you wish to be entirely
 portable define `ED25519_NO_SEED`. This disables the `ed25519_create_seed`
 function, so if your application requires key generation you must supply your
 own seeding function (simply a 32 byte random number generator).