diff --git a/sihl/src/dune b/sihl/src/dune
index f3e41766..4c432250 100644
--- a/sihl/src/dune
+++ b/sihl/src/dune
@@ -4,7 +4,7 @@
  (libraries sexplib fmt fmt.tty logs logs.fmt lwt lwt.unix tsort conformist
    base64 yojson ppx_deriving_yojson.runtime safepass ptime ptime.clock.os
    jwto uuidm opium caqti-lwt caqti-lwt.unix str dune-build-info bos
-   containers mirage-crypto mirage-crypto-rng cstruct)
+   containers mirage-crypto mirage-crypto-rng mirage-crypto-rng.unix cstruct)
  (preprocess
   (pps ppx_fields_conv ppx_deriving_yojson ppx_deriving.eq ppx_deriving.show
     ppx_deriving.make ppx_sexp_conv lwt_ppx)))
diff --git a/sihl/src/web_csrf.ml b/sihl/src/web_csrf.ml
index 5c17360d..73cdd7c3 100644
--- a/sihl/src/web_csrf.ml
+++ b/sihl/src/web_csrf.ml
@@ -33,6 +33,7 @@ let set token req =
  *)
 
 module Crypto = struct
+  let () = Mirage_crypto_rng_unix.initialize (module Mirage_crypto_rng.Fortuna)
   let block_size = 16
 
   (** [token_length] is the amount of bytes used in the unencrypted CSRF tokens. *)