diff --git a/nimue-pow/Cargo.toml b/nimue-pow/Cargo.toml
index 550898a..3b227d3 100644
--- a/nimue-pow/Cargo.toml
+++ b/nimue-pow/Cargo.toml
@@ -14,6 +14,7 @@ blake3 = "1.5.4"
 keccak = { version = "0.1.4"}
 bytemuck = "1.17.1"
 rayon = { version = "1.10.0", optional = true }
+rand = "0.8.5"
 
 [features]
 default = ["parallel"]
diff --git a/nimue-pow/src/blake3.rs b/nimue-pow/src/blake3.rs
index 7c928bf..fa448de 100644
--- a/nimue-pow/src/blake3.rs
+++ b/nimue-pow/src/blake3.rs
@@ -144,11 +144,12 @@ impl Blake3PoW {
 
 #[test]
 fn test_pow_blake3() {
-    use crate::{ByteIOPattern, ByteReader, ByteWriter, IOPattern, PoWChallenge, PoWIOPattern};
+    use crate::{ByteIOPattern, ByteReader, ByteWriter, PoWChallenge, PoWIOPattern};
+    use nimue::{DefaultHash, IOPattern};
 
     const BITS: f64 = 10.0;
 
-    let iopattern = IOPattern::new("the proof of work lottery 🎰")
+    let iopattern = IOPattern::<DefaultHash>::new("the proof of work lottery 🎰")
         .add_bytes(1, "something")
         .challenge_pow("rolling dices");
 
diff --git a/nimue-pow/src/keccak.rs b/nimue-pow/src/keccak.rs
index 29a010f..b5c37d4 100644
--- a/nimue-pow/src/keccak.rs
+++ b/nimue-pow/src/keccak.rs
@@ -30,11 +30,12 @@ impl PowStrategy for KeccakPoW {
 
 #[test]
 fn test_pow_keccak() {
-    use crate::{ByteIOPattern, ByteReader, ByteWriter, IOPattern, PoWChallenge, PoWIOPattern};
+    use crate::{ByteIOPattern, ByteReader, ByteWriter, PoWChallenge, PoWIOPattern};
+    use nimue::{DefaultHash, IOPattern};
 
     const BITS: f64 = 10.0;
 
-    let iopattern = IOPattern::new("the proof of work lottery 🎰")
+    let iopattern = IOPattern::<DefaultHash>::new("the proof of work lottery 🎰")
         .add_bytes(1, "something")
         .challenge_pow("rolling dices");
 
diff --git a/nimue-pow/src/lib.rs b/nimue-pow/src/lib.rs
index df26924..5b0c3a5 100644
--- a/nimue-pow/src/lib.rs
+++ b/nimue-pow/src/lib.rs
@@ -2,8 +2,8 @@ pub mod blake3;
 pub mod keccak;
 
 use nimue::{
-    Arthur, ByteChallenges, ByteIOPattern, ByteReader, ByteWriter, IOPattern, Merlin, ProofError,
-    ProofResult,
+    Arthur, ByteChallenges, ByteIOPattern, ByteReader, ByteWriter, DuplexHash, Merlin, ProofError,
+    ProofResult, Unit,
 };
 
 /// [`IOPattern`] for proof-of-work challenges.
@@ -21,7 +21,10 @@ pub trait PoWIOPattern {
     fn challenge_pow(self, label: &str) -> Self;
 }
 
-impl PoWIOPattern for IOPattern {
+impl<IOPattern> PoWIOPattern for IOPattern
+where
+    IOPattern: ByteIOPattern,
+{
     fn challenge_pow(self, label: &str) -> Self {
         // 16 bytes challenge and 16 bytes nonce (that will be written)
         self.challenge_bytes(32, label).add_bytes(8, "pow-nonce")
@@ -33,9 +36,12 @@ pub trait PoWChallenge {
     fn challenge_pow<S: PowStrategy>(&mut self, bits: f64) -> ProofResult<()>;
 }
 
-impl PoWChallenge for Merlin
+impl<H, U, R> PoWChallenge for Merlin<H, U, R>
 where
-    Merlin: ByteWriter,
+    U: Unit,
+    H: DuplexHash<U>,
+    R: rand::CryptoRng + rand::RngCore,
+    Merlin<H, U, R>: ByteWriter + ByteChallenges,
 {
     fn challenge_pow<S: PowStrategy>(&mut self, bits: f64) -> ProofResult<()> {
         let challenge = self.challenge_bytes()?;
@@ -47,9 +53,11 @@ where
     }
 }
 
-impl<'a> PoWChallenge for Arthur<'a>
+impl<'a, H, U> PoWChallenge for Arthur<'a, H, U>
 where
-    Arthur<'a>: ByteReader,
+    U: Unit,
+    H: DuplexHash<U>,
+    Arthur<'a, H, U>: ByteReader + ByteChallenges,
 {
     fn challenge_pow<S: PowStrategy>(&mut self, bits: f64) -> ProofResult<()> {
         let challenge = self.challenge_bytes()?;
diff --git a/nimue/src/plugins/ark/common.rs b/nimue/src/plugins/ark/common.rs
index 9a48030..9fd4d96 100644
--- a/nimue/src/plugins/ark/common.rs
+++ b/nimue/src/plugins/ark/common.rs
@@ -78,7 +78,7 @@ where
 impl<F, T> FieldChallenges<F> for T
 where
     F: Field,
-    T: ByteChallenges,
+    T: UnitTranscript<u8>,
 {
     fn fill_challenge_scalars(&mut self, output: &mut [F]) -> ProofResult<()> {
         let base_field_size = bytes_uniform_modp(F::BasePrimeField::MODULUS_BIT_SIZE);
@@ -96,6 +96,29 @@ where
     }
 }
 
+impl<H, C, const N: usize> FieldChallenges<Fp<C, N>> for Arthur<'_, H, Fp<C, N>>
+where
+    C: FpConfig<N>,
+    H: DuplexHash<Fp<C, N>>,
+{
+    fn fill_challenge_scalars(&mut self, output: &mut [Fp<C, N>]) -> ProofResult<()> {
+        self.fill_challenge_units(output)
+            .map_err(ProofError::InvalidIO)
+    }
+}
+
+impl<H, C, R, const N: usize> FieldChallenges<Fp<C, N>> for Merlin<H, Fp<C, N>, R>
+where
+    C: FpConfig<N>,
+    H: DuplexHash<Fp<C, N>>,
+    R: CryptoRng + RngCore,
+{
+    fn fill_challenge_scalars(&mut self, output: &mut [Fp<C, N>]) -> ProofResult<()> {
+        self.fill_challenge_units(output)
+            .map_err(ProofError::InvalidIO)
+    }
+}
+
 // Field <-> Field interactions:
 
 impl<F, H, R, C, const N: usize> FieldPublic<F> for Merlin<H, Fp<C, N>, R>
@@ -191,7 +214,7 @@ where
 
 // Field  <-> Bytes interactions:
 
-impl<'a, H, C, const N: usize> BytePublic for Arthur<'a, H, Fp<C, N>>
+impl<H, C, const N: usize> BytePublic for Arthur<'_, H, Fp<C, N>>
 where
     C: FpConfig<N>,
     H: DuplexHash<Fp<C, N>>,
@@ -222,7 +245,7 @@ impl<H, R, C, const N: usize> ByteChallenges for Merlin<H, Fp<C, N>, R>
 where
     C: FpConfig<N>,
     H: DuplexHash<Fp<C, N>>,
-    R: CryptoRng + rand::RngCore,
+    R: CryptoRng + RngCore,
 {
     fn fill_challenge_bytes(&mut self, output: &mut [u8]) -> Result<(), IOPatternError> {
         if output.is_empty() {
@@ -244,7 +267,7 @@ where
 }
 
 /// XXX. duplicate code
-impl<'a, H, C, const N: usize> ByteChallenges for Arthur<'a, H, Fp<C, N>>
+impl<H, C, const N: usize> ByteChallenges for Arthur<'_, H, Fp<C, N>>
 where
     C: FpConfig<N>,
     H: DuplexHash<Fp<C, N>>,
diff --git a/nimue/src/plugins/ark/writer.rs b/nimue/src/plugins/ark/writer.rs
index 8d3e3eb..1742986 100644
--- a/nimue/src/plugins/ark/writer.rs
+++ b/nimue/src/plugins/ark/writer.rs
@@ -4,7 +4,10 @@ use ark_serialize::CanonicalSerialize;
 use rand::{CryptoRng, RngCore};
 
 use super::{FieldPublic, FieldWriter, GroupPublic, GroupWriter};
-use crate::{DuplexHash, Merlin, ProofResult, UnitTranscript};
+use crate::{
+    Arthur, BytePublic, ByteReader, ByteWriter, DuplexHash, IOPatternError, Merlin, ProofResult,
+    Unit, UnitTranscript,
+};
 
 impl<F: Field, H: DuplexHash, R: RngCore + CryptoRng> FieldWriter<F> for Merlin<H, u8, R> {
     fn add_scalars(&mut self, input: &[F]) -> ProofResult<()> {
@@ -58,3 +61,27 @@ where
         Ok(())
     }
 }
+
+impl<H, R, C, const N: usize> ByteWriter for Merlin<H, Fp<C, N>, R>
+where
+    H: DuplexHash<Fp<C, N>>,
+    C: FpConfig<N>,
+    R: RngCore + CryptoRng,
+{
+    fn add_bytes(&mut self, input: &[u8]) -> Result<(), IOPatternError> {
+        self.public_bytes(input)?;
+        self.transcript.extend(input);
+        Ok(())
+    }
+}
+
+impl<'a, H, C, const N: usize> ByteReader for Arthur<'a, H, Fp<C, N>>
+where
+    H: DuplexHash<Fp<C, N>>,
+    C: FpConfig<N>,
+{
+    fn fill_next_bytes(&mut self, input: &mut [u8]) -> Result<(), IOPatternError> {
+        u8::read(&mut self.transcript, input)?;
+        self.public_bytes(input)
+    }
+}