diff --git a/src/signatures.ml b/src/signatures.ml
index 80cebad6..1d57405e 100644
--- a/src/signatures.ml
+++ b/src/signatures.ml
@@ -1,9 +1,7 @@
 (* TODO signatures
-   check with taler-wallet-core/src/crypto/cryptoImplementation.js
+   check with taler-wallet
    check signed/unsigned ints
-   check endianness
-
-   better handling of decoding failure *)
+   check endianness *)
 open Hash
 
 module Aliases = struct
@@ -177,8 +175,9 @@ end = struct
   type r = R.r
   type t = EddsaSignature.t
 
-  let sign_f ~f r = f (Bin.to_string R.bin r)
-  let verify_f ~f t r = f t ~msg:(Bin.to_string R.bin r)
+  let to_string = Bin.to_string R.bin
+  let sign_f ~f r = f (to_string r)
+  let verify_f ~f t r = f t ~msg:(to_string r)
   let jsont = EddsaSignature.jsont
   let caqti : EddsaSignature.t Caqti_type.t = EddsaSignature.caqti
   let to_octets t = EddsaSignature.to_octets t