diff --git a/README.md b/README.md
index 47f9167..0be8a8d 100644
--- a/README.md
+++ b/README.md
@@ -406,6 +406,7 @@ encryption library providing MD5, SHA1, SHA2 hashing and HMAC functionality, as
 
 ### Scheme
 
+- [crypto-tools](https://wiki.call-cc.org/eggref/5/crypto-tools) - Useful cryptographic primitives for Chicken Scheme.
 - [guile-gnutls](https://gitlab.com/gnutls/guile/) - GnuTLS bindings for GNU Guile.
 - [guile-ssh](https://github.com/artyom-poptsov/guile-ssh) - libssh bindings for GNU Guile.