diff --git a/src/envelope.rs b/src/envelope.rs
index 172a17c..216f14e 100644
--- a/src/envelope.rs
+++ b/src/envelope.rs
@@ -32,7 +32,7 @@ const NONCE_LEN: usize = 32;
 fn build_inner_envelope_internal<CS: CipherSuite>(
     random_pwd: &[u8],
     nonce: &[u8],
-) -> Result<PublicKey<CS::Group>, InternalPakeError> {
+) -> Result<PublicKey<CS::Group>, ProtocolError> {
     let h = Hkdf::<CS::Hash>::new(None, random_pwd);
     let mut keypair_seed = vec![0u8; <PrivateKey<CS::Group> as SizedBytes>::Len::to_usize()];
     h.expand(&[nonce, STR_PRIVATE_KEY].concat(), &mut keypair_seed)
@@ -48,7 +48,7 @@ fn build_inner_envelope_internal<CS: CipherSuite>(
 fn recover_keys_internal<CS: CipherSuite>(
     random_pwd: &[u8],
     nonce: &[u8],
-) -> Result<KeyPair<CS::Group>, InternalPakeError> {
+) -> Result<KeyPair<CS::Group>, ProtocolError> {
     let h = Hkdf::<CS::Hash>::new(None, random_pwd);
     let mut keypair_seed = vec![0u8; <PrivateKey<CS::Group> as SizedBytes>::Len::to_usize()];
     h.expand(&[nonce, STR_PRIVATE_KEY].concat(), &mut keypair_seed)
@@ -188,7 +188,7 @@ impl<CS: CipherSuite> Envelope<CS> {
             PublicKey<CS::Group>,
             GenericArray<u8, <CS::Hash as Digest>::OutputSize>,
         ),
-        InternalPakeError,
+        ProtocolError,
     > {
         let mut nonce = vec![0u8; NONCE_LEN];
         rng.fill_bytes(&mut nonce);
@@ -199,7 +199,7 @@ impl<CS: CipherSuite> Envelope<CS> {
         );
 
         let (id_u, id_s) =
-            bytestrings_from_identifiers(&optional_ids, &client_s_pk.to_arr(), server_s_pk);
+            bytestrings_from_identifiers(&optional_ids, &client_s_pk.to_arr(), server_s_pk)?;
         let aad = construct_aad(&id_u, &id_s, server_s_pk);
 
         let (envelope, export_key) = Self::seal_raw(key, &nonce, &aad, mode)?;
@@ -246,10 +246,10 @@ impl<CS: CipherSuite> Envelope<CS> {
         key: &[u8],
         server_s_pk: &[u8],
         optional_ids: &Option<Identifiers>,
-    ) -> Result<OpenedEnvelope<CS>, InternalPakeError> {
+    ) -> Result<OpenedEnvelope<CS>, ProtocolError> {
         let client_static_keypair = match self.mode {
             InnerEnvelopeMode::Zero => {
-                return Err(InternalPakeError::IncompatibleEnvelopeModeError)
+                return Err(InternalPakeError::IncompatibleEnvelopeModeError.into())
             }
             InnerEnvelopeMode::Internal => recover_keys_internal::<CS>(key, &self.nonce)?,
         };
@@ -258,7 +258,7 @@ impl<CS: CipherSuite> Envelope<CS> {
             optional_ids,
             &client_static_keypair.public().to_arr(),
             server_s_pk,
-        );
+        )?;
         let aad = construct_aad(&id_u, &id_s, server_s_pk);
 
         let opened = self.open_raw(key, &aad)?;
diff --git a/src/key_exchange/tripledh.rs b/src/key_exchange/tripledh.rs
index 5d0da1f..e477848 100644
--- a/src/key_exchange/tripledh.rs
+++ b/src/key_exchange/tripledh.rs
@@ -86,7 +86,7 @@ impl<D: Hash, G: Group> KeyExchange<D, G> for TripleDH {
 
         let mut transcript_hasher = D::new()
             .chain(STR_RFC)
-            .chain(&serialize(&context, 2))
+            .chain(&serialize(&context, 2)?)
             .chain(&id_u)
             .chain(&serialized_credential_request[..])
             .chain(&id_s)
@@ -141,7 +141,7 @@ impl<D: Hash, G: Group> KeyExchange<D, G> for TripleDH {
     ) -> Result<(Vec<u8>, Self::KE3Message), ProtocolError> {
         let mut transcript_hasher = D::new()
             .chain(STR_RFC)
-            .chain(&serialize(&context, 2))
+            .chain(&serialize(&context, 2)?)
             .chain(&id_u)
             .chain(&serialized_credential_request)
             .chain(&id_s)
@@ -522,9 +522,9 @@ fn hkdf_expand_label_extracted<D: Hash>(
     let mut opaque_label: Vec<u8> = Vec::new();
     opaque_label.extend_from_slice(STR_OPAQUE);
     opaque_label.extend_from_slice(label);
-    hkdf_label.extend_from_slice(&serialize(&opaque_label, 1));
+    hkdf_label.extend_from_slice(&serialize(&opaque_label, 1)?);
 
-    hkdf_label.extend_from_slice(&serialize(context, 1));
+    hkdf_label.extend_from_slice(&serialize(context, 1)?);
 
     hkdf.expand(&hkdf_label, &mut okm)
         .map_err(|_| InternalPakeError::HkdfError)?;
diff --git a/src/map_to_curve.rs b/src/map_to_curve.rs
index 7bbb40a..42b8730 100644
--- a/src/map_to_curve.rs
+++ b/src/map_to_curve.rs
@@ -6,7 +6,7 @@
 //! Defines the GroupWithMapToCurve trait to specify how to map a password to a
 //! curve point
 
-use crate::errors::InternalPakeError;
+use crate::errors::{InternalPakeError, ProtocolError};
 use crate::group::Group;
 use crate::hash::Hash;
 use crate::serialization::i2osp;
@@ -22,16 +22,15 @@ pub trait GroupWithMapToCurve: Group {
     const SUITE_ID: usize;
 
     /// transforms a password and domain separation tag (DST) into a curve point
-    fn map_to_curve<H: Hash>(msg: &[u8], dst: &[u8]) -> Result<Self, InternalPakeError>;
+    fn map_to_curve<H: Hash>(msg: &[u8], dst: &[u8]) -> Result<Self, ProtocolError>;
 
     /// Hashes a slice of pseudo-random bytes to a scalar
-    fn hash_to_scalar<H: Hash>(input: &[u8], dst: &[u8])
-        -> Result<Self::Scalar, InternalPakeError>;
+    fn hash_to_scalar<H: Hash>(input: &[u8], dst: &[u8]) -> Result<Self::Scalar, ProtocolError>;
 
     /// Generates the contextString parameter as defined in
     /// <https://www.ietf.org/archive/id/draft-irtf-cfrg-voprf-05.txt>
-    fn get_context_string(mode: u8) -> Vec<u8> {
-        [i2osp(mode as usize, 1), i2osp(Self::SUITE_ID, 2)].concat()
+    fn get_context_string(mode: u8) -> Result<Vec<u8>, ProtocolError> {
+        Ok([i2osp(mode as usize, 1)?, i2osp(Self::SUITE_ID, 2)?].concat())
     }
 }
 
@@ -40,16 +39,14 @@ impl GroupWithMapToCurve for RistrettoPoint {
 
     // Implements the hash_to_ristretto255() function from
     // https://www.ietf.org/archive/id/draft-irtf-cfrg-hash-to-curve-10.txt
-    fn map_to_curve<H: Hash>(msg: &[u8], dst: &[u8]) -> Result<Self, InternalPakeError> {
+    fn map_to_curve<H: Hash>(msg: &[u8], dst: &[u8]) -> Result<Self, ProtocolError> {
         let uniform_bytes =
             expand_message_xmd::<H>(msg, dst, <H as Digest>::OutputSize::to_usize())?;
         <Self as Group>::hash_to_curve(&GenericArray::clone_from_slice(&uniform_bytes[..]))
+            .map_err(ProtocolError::from)
     }
 
-    fn hash_to_scalar<H: Hash>(
-        input: &[u8],
-        dst: &[u8],
-    ) -> Result<Self::Scalar, InternalPakeError> {
+    fn hash_to_scalar<H: Hash>(input: &[u8], dst: &[u8]) -> Result<Self::Scalar, ProtocolError> {
         const LEN_IN_BYTES: usize = 64;
         let uniform_bytes = expand_message_xmd::<H>(input, dst, LEN_IN_BYTES)?;
         let mut bits = [0u8; LEN_IN_BYTES];
@@ -79,24 +76,24 @@ pub fn expand_message_xmd<H: Hash>(
     msg: &[u8],
     dst: &[u8],
     len_in_bytes: usize,
-) -> Result<Vec<u8>, InternalPakeError> {
+) -> Result<Vec<u8>, ProtocolError> {
     let b_in_bytes = <H as Digest>::OutputSize::to_usize();
     let r_in_bytes = <H as BlockInput>::BlockSize::to_usize();
 
     let ell = div_ceil(len_in_bytes, b_in_bytes);
     if ell > 255 {
-        return Err(InternalPakeError::HashToCurveError);
+        return Err(InternalPakeError::HashToCurveError.into());
     }
-    let dst_prime = [dst, &i2osp(dst.len(), 1)].concat();
-    let z_pad = i2osp(0, r_in_bytes);
-    let l_i_b_str = i2osp(len_in_bytes, 2);
-    let msg_prime = [&z_pad, msg, &l_i_b_str, &i2osp(0, 1), &dst_prime].concat();
+    let dst_prime = [dst, &i2osp(dst.len(), 1)?].concat();
+    let z_pad = i2osp(0, r_in_bytes)?;
+    let l_i_b_str = i2osp(len_in_bytes, 2)?;
+    let msg_prime = [&z_pad, msg, &l_i_b_str, &i2osp(0, 1)?, &dst_prime].concat();
 
     let mut b: Vec<Vec<u8>> = vec![H::digest(&msg_prime).to_vec()]; // b[0]
 
     let mut h = H::new();
     h.update(&b[0]);
-    h.update(&i2osp(1, 1));
+    h.update(&i2osp(1, 1)?);
     h.update(&dst_prime);
     b.push(h.finalize_reset().to_vec()); // b[1]
 
@@ -105,7 +102,7 @@ pub fn expand_message_xmd<H: Hash>(
 
     for i in 2..(ell + 1) {
         h.update(xor(&b[0], &b[i - 1])?);
-        h.update(&i2osp(i, 1));
+        h.update(&i2osp(i, 1)?);
         h.update(&dst_prime);
         b.push(h.finalize_reset().to_vec()); // b[i]
         uniform_bytes.extend_from_slice(&b[i]);
diff --git a/src/opaque.rs b/src/opaque.rs
index 48c9f40..24d8493 100644
--- a/src/opaque.rs
+++ b/src/opaque.rs
@@ -174,17 +174,17 @@ pub(crate) fn bytestrings_from_identifiers(
     ids: &Option<Identifiers>,
     client_s_pk: &[u8],
     server_s_pk: &[u8],
-) -> (Vec<u8>, Vec<u8>) {
+) -> Result<(Vec<u8>, Vec<u8>), ProtocolError> {
     let (client_identity, server_identity): (Vec<u8>, Vec<u8>) = match ids {
         None => (client_s_pk.to_vec(), server_s_pk.to_vec()),
         Some(Identifiers::ClientIdentifier(id_u)) => (id_u.clone(), server_s_pk.to_vec()),
         Some(Identifiers::ServerIdentifier(id_s)) => (client_s_pk.to_vec(), id_s.clone()),
         Some(Identifiers::ClientAndServerIdentifiers(id_u, id_s)) => (id_u.clone(), id_s.clone()),
     };
-    (
-        serialize(&client_identity, 2),
-        serialize(&server_identity, 2),
-    )
+    Ok((
+        serialize(&client_identity, 2)?,
+        serialize(&server_identity, 2)?,
+    ))
 }
 
 /// Optional parameters for client registration finish
@@ -413,15 +413,15 @@ impl_debug_eq_hash_for!(
 
 impl<CS: CipherSuite> ClientLogin<CS> {
     /// Serialization into bytes
-    pub fn serialize(&self) -> Vec<u8> {
+    pub fn serialize(&self) -> Result<Vec<u8>, ProtocolError> {
         let output: Vec<u8> = [
             &CS::Group::scalar_as_bytes(self.token.blind)[..],
-            &serialize(&self.serialized_credential_request, 2),
-            &serialize(&self.ke1_state.to_bytes(), 2),
+            &serialize(&self.serialized_credential_request, 2)?,
+            &serialize(&self.ke1_state.to_bytes(), 2)?,
             &self.token.data,
         ]
         .concat();
-        output
+        Ok(output)
     }
 
     /// Deserialization from bytes
@@ -604,8 +604,10 @@ impl<CS: CipherSuite> ClientLogin<CS> {
         let opened_envelope = &envelope
             .open(&password_derived_key, &server_s_pk_bytes, &optional_ids)
             .map_err(|e| match e {
-                InternalPakeError::SealOpenHmacError => PakeError::InvalidLoginError,
-                err => PakeError::from(err),
+                ProtocolError::VerificationError(PakeError::CryptoError(
+                    InternalPakeError::SealOpenHmacError,
+                )) => ProtocolError::VerificationError(PakeError::InvalidLoginError),
+                err => err,
             })?;
 
         let credential_response_component = CredentialResponse::<CS>::serialize_without_ke(
@@ -767,7 +769,7 @@ impl<CS: CipherSuite> ServerLogin<CS> {
             &optional_ids,
             &client_s_pk.to_arr(),
             &server_s_pk.to_arr(),
-        );
+        )?;
 
         let l1_bytes = &l1.serialize();
 
@@ -906,15 +908,15 @@ impl<CS: CipherSuite> Drop for ServerLogin<CS> {
 fn get_password_derived_key<G: GroupWithMapToCurve, SH: SlowHash<D>, D: Hash>(
     token: &oprf::Token<G>,
     beta: G,
-) -> Result<Vec<u8>, InternalPakeError> {
-    let oprf_output = oprf::finalize::<G, D>(&token.data, &token.blind, beta);
-    SH::hash(oprf_output)
+) -> Result<Vec<u8>, ProtocolError> {
+    let oprf_output = oprf::finalize::<G, D>(&token.data, &token.blind, beta)?;
+    SH::hash(oprf_output).map_err(ProtocolError::from)
 }
 
 fn oprf_key_from_seed<G: GroupWithMapToCurve, D: Hash>(
     oprf_seed: &GenericArray<u8, D::OutputSize>,
     credential_identifier: &[u8],
-) -> Result<G::Scalar, InternalPakeError> {
+) -> Result<G::Scalar, ProtocolError> {
     let mut oprf_key_bytes = vec![0u8; <PrivateKey<G> as SizedBytes>::Len::to_usize()];
     Hkdf::<D>::from_prk(oprf_seed)
         .map_err(|_| InternalPakeError::HkdfError)?
diff --git a/src/oprf.rs b/src/oprf.rs
index 08f225b..4a6230f 100644
--- a/src/oprf.rs
+++ b/src/oprf.rs
@@ -4,7 +4,7 @@
 // LICENSE file in the root directory of this source tree.
 
 use crate::{
-    errors::InternalPakeError, group::Group, hash::Hash, map_to_curve::GroupWithMapToCurve,
+    errors::ProtocolError, group::Group, hash::Hash, map_to_curve::GroupWithMapToCurve,
     serialization::serialize,
 };
 use digest::Digest;
@@ -32,10 +32,10 @@ static MODE_BASE: u8 = 0x00;
 pub(crate) fn blind<R: RngCore + CryptoRng, G: GroupWithMapToCurve, H: Hash>(
     input: &[u8],
     blinding_factor_rng: &mut R,
-) -> Result<(Token<G>, G), InternalPakeError> {
+) -> Result<(Token<G>, G), ProtocolError> {
     // Choose a random scalar that must be non-zero
     let blind = G::random_nonzero_scalar(blinding_factor_rng);
-    let dst = [STR_VOPRF, &G::get_context_string(MODE_BASE)].concat();
+    let dst = [STR_VOPRF, &G::get_context_string(MODE_BASE)?].concat();
     let mapped_point = G::map_to_curve::<H>(input, &dst)?;
     let blind_token = mapped_point * &blind;
     Ok((
@@ -59,7 +59,7 @@ pub(crate) fn finalize<G: GroupWithMapToCurve, H: Hash>(
     input: &[u8],
     blind: &G::Scalar,
     evaluated_element: G,
-) -> GenericArray<u8, <H as Digest>::OutputSize> {
+) -> Result<GenericArray<u8, <H as Digest>::OutputSize>, ProtocolError> {
     let unblinded_element = evaluated_element * &G::scalar_invert(blind);
     finalize_after_unblind::<G, H>(input, unblinded_element)
 }
@@ -67,15 +67,15 @@ pub(crate) fn finalize<G: GroupWithMapToCurve, H: Hash>(
 fn finalize_after_unblind<G: GroupWithMapToCurve, H: Hash>(
     input: &[u8],
     unblinded_element: G,
-) -> GenericArray<u8, <H as Digest>::OutputSize> {
-    let finalize_dst = [STR_VOPRF_FINALIZE, &G::get_context_string(MODE_BASE)].concat();
+) -> Result<GenericArray<u8, <H as Digest>::OutputSize>, ProtocolError> {
+    let finalize_dst = [STR_VOPRF_FINALIZE, &G::get_context_string(MODE_BASE)?].concat();
     let hash_input = [
-        serialize(input, 2),
-        serialize(&unblinded_element.to_arr().to_vec(), 2),
-        serialize(&finalize_dst, 2),
+        serialize(input, 2)?,
+        serialize(&unblinded_element.to_arr().to_vec(), 2)?,
+        serialize(&finalize_dst, 2)?,
     ]
     .concat();
-    <H as Digest>::digest(&hash_input)
+    Ok(<H as Digest>::digest(&hash_input))
 }
 
 ////////////////////////
@@ -88,7 +88,7 @@ fn finalize_after_unblind<G: GroupWithMapToCurve, H: Hash>(
 pub fn blind_shim<R: RngCore + CryptoRng, G: GroupWithMapToCurve, H: Hash>(
     input: &[u8],
     blinding_factor_rng: &mut R,
-) -> Result<(Token<G>, G), InternalPakeError> {
+) -> Result<(Token<G>, G), ProtocolError> {
     blind::<R, G, H>(input, blinding_factor_rng)
 }
 
@@ -105,8 +105,8 @@ pub fn evaluate_shim<G: Group>(point: G, oprf_key: &G::Scalar) -> G {
 pub fn finalize_shim<G: GroupWithMapToCurve, H: Hash>(
     token: &Token<G>,
     point: G,
-) -> Result<GenericArray<u8, <H as Digest>::OutputSize>, InternalPakeError> {
-    Ok(finalize::<G, H>(&token.data, &token.blind, point))
+) -> Result<GenericArray<u8, <H as Digest>::OutputSize>, ProtocolError> {
+    finalize::<G, H>(&token.data, &token.blind, point)
 }
 
 ///////////
@@ -124,30 +124,34 @@ mod tests {
     use sha2::Sha512;
 
     fn prf(input: &[u8], oprf_key: &[u8; 32]) -> GenericArray<u8, <Sha512 as Digest>::OutputSize> {
-        let dst = [STR_VOPRF, &RistrettoPoint::get_context_string(MODE_BASE)].concat();
+        let dst = [
+            STR_VOPRF,
+            &RistrettoPoint::get_context_string(MODE_BASE).unwrap(),
+        ]
+        .concat();
         let point = RistrettoPoint::map_to_curve::<Sha512>(input, &dst).unwrap();
         let scalar =
             RistrettoPoint::from_scalar_slice(GenericArray::from_slice(&oprf_key[..])).unwrap();
         let res = point * scalar;
 
-        finalize_after_unblind::<RistrettoPoint, sha2::Sha512>(&input, res)
+        finalize_after_unblind::<RistrettoPoint, sha2::Sha512>(&input, res).unwrap()
     }
 
     #[test]
-    fn oprf_retrieval() -> Result<(), InternalPakeError> {
+    fn oprf_retrieval() {
         let input = b"hunter2";
         let mut rng = OsRng;
-        let (token, alpha) = blind::<_, RistrettoPoint, Sha512>(&input[..], &mut rng)?;
+        let (token, alpha) = blind::<_, RistrettoPoint, Sha512>(&input[..], &mut rng).unwrap();
         let oprf_key_bytes = arr![
             u8; 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23,
             24, 25, 26, 27, 28, 29, 30, 31, 32,
         ];
-        let oprf_key = RistrettoPoint::from_scalar_slice(&oprf_key_bytes)?;
+        let oprf_key = RistrettoPoint::from_scalar_slice(&oprf_key_bytes).unwrap();
         let beta = evaluate::<RistrettoPoint>(alpha, &oprf_key);
-        let res = finalize::<RistrettoPoint, sha2::Sha512>(&token.data, &token.blind, beta);
+        let res =
+            finalize::<RistrettoPoint, sha2::Sha512>(&token.data, &token.blind, beta).unwrap();
         let res2 = prf(&input[..], &oprf_key.as_bytes());
         assert_eq!(res, res2);
-        Ok(())
     }
 
     #[test]
@@ -156,11 +160,16 @@ mod tests {
         let mut input = vec![0u8; 64];
         rng.fill_bytes(&mut input);
         let (token, alpha) = blind::<_, RistrettoPoint, sha2::Sha512>(&input, &mut rng).unwrap();
-        let res = finalize::<RistrettoPoint, sha2::Sha512>(&token.data, &token.blind, alpha);
+        let res =
+            finalize::<RistrettoPoint, sha2::Sha512>(&token.data, &token.blind, alpha).unwrap();
 
-        let dst = [STR_VOPRF, &RistrettoPoint::get_context_string(MODE_BASE)].concat();
+        let dst = [
+            STR_VOPRF,
+            &RistrettoPoint::get_context_string(MODE_BASE).unwrap(),
+        ]
+        .concat();
         let point = RistrettoPoint::map_to_curve::<Sha512>(&input, &dst).unwrap();
-        let res2 = finalize_after_unblind::<RistrettoPoint, sha2::Sha512>(&input, point);
+        let res2 = finalize_after_unblind::<RistrettoPoint, sha2::Sha512>(&input, point).unwrap();
 
         assert_eq!(res, res2);
     }
diff --git a/src/serialization/mod.rs b/src/serialization/mod.rs
index 38d45da..ed65a83 100644
--- a/src/serialization/mod.rs
+++ b/src/serialization/mod.rs
@@ -6,17 +6,24 @@
 use crate::errors::PakeError;
 
 // Corresponds to the I2OSP() function from RFC8017
-pub(crate) fn i2osp(input: usize, length: usize) -> Vec<u8> {
-    if length <= std::mem::size_of::<usize>() {
-        return (&input.to_be_bytes()[std::mem::size_of::<usize>() - length..]).to_vec();
+pub(crate) fn i2osp(input: usize, length: usize) -> Result<Vec<u8>, PakeError> {
+    let sizeof_usize = std::mem::size_of::<usize>();
+
+    // Check if input >= 256^length
+    if (sizeof_usize as u32 - input.leading_zeros() / 8) > length as u32 {
+        return Err(PakeError::SerializationError);
+    }
+
+    if length <= sizeof_usize {
+        return Ok((&input.to_be_bytes()[sizeof_usize - length..]).to_vec());
     }
 
     let mut output = vec![0u8; length];
     output.splice(
-        length - std::mem::size_of::<usize>()..length,
+        length - sizeof_usize..length,
         input.to_be_bytes().iter().cloned(),
     );
-    output
+    Ok(output)
 }
 
 // Corresponds to the OS2IP() function from RFC8017
@@ -31,8 +38,8 @@ pub(crate) fn os2ip(input: &[u8]) -> Result<usize, PakeError> {
 }
 
 // Computes I2OSP(len(input), max_bytes) || input
-pub(crate) fn serialize(input: &[u8], max_bytes: usize) -> Vec<u8> {
-    [&i2osp(input.len(), max_bytes), input].concat()
+pub(crate) fn serialize(input: &[u8], max_bytes: usize) -> Result<Vec<u8>, PakeError> {
+    Ok([&i2osp(input.len(), max_bytes)?, input].concat())
 }
 
 // Tokenizes an input of the format I2OSP(len(input), max_bytes) || input, outputting
@@ -122,3 +129,22 @@ macro_rules! impl_serialize_and_deserialize_for {
 
 #[cfg(test)]
 mod tests;
+
+#[cfg(test)]
+mod unit_tests {
+    use super::*;
+
+    // Test the error condition for I2OSP
+    #[test]
+    fn test_i2osp_err_check() {
+        assert!(i2osp(0, 1).is_ok());
+
+        assert!(i2osp(255, 1).is_ok());
+        assert!(i2osp(256, 1).is_err());
+        assert!(i2osp(257, 1).is_err());
+
+        assert!(i2osp(256 * 256 - 1, 2).is_ok());
+        assert!(i2osp(256 * 256, 2).is_err());
+        assert!(i2osp(256 * 256 + 1, 2).is_err());
+    }
+}
diff --git a/src/serialization/tests.rs b/src/serialization/tests.rs
index 202dcf7..4a60b96 100644
--- a/src/serialization/tests.rs
+++ b/src/serialization/tests.rs
@@ -283,13 +283,13 @@ fn client_login_roundtrip() {
     // serialization order: scalar, credential_request, ke1_state, password
     let bytes: Vec<u8> = [
         &sc.as_bytes()[..],
-        &serialize(&serialized_credential_request, 2),
-        &serialize(&l1_data, 2),
+        &serialize(&serialized_credential_request, 2).unwrap(),
+        &serialize(&l1_data, 2).unwrap(),
         &pw[..],
     ]
     .concat();
     let reg = ClientLogin::<Default>::deserialize(&bytes[..]).unwrap();
-    let reg_bytes = reg.serialize();
+    let reg_bytes = reg.serialize().unwrap();
     assert_eq!(reg_bytes, bytes);
 }
 
@@ -350,7 +350,7 @@ proptest! {
 
 #[test]
 fn test_i2osp_os2ip(bytes in vec(any::<u8>(), 0..std::mem::size_of::<usize>())) {
-    assert_eq!(i2osp(os2ip(&bytes)?, bytes.len()), bytes);
+    assert_eq!(i2osp(os2ip(&bytes)?, bytes.len())?, bytes);
 }
 
 #[test]
diff --git a/src/tests/full_test.rs b/src/tests/full_test.rs
index 5ec44c7..7e3d48e 100644
--- a/src/tests/full_test.rs
+++ b/src/tests/full_test.rs
@@ -368,7 +368,11 @@ fn generate_parameters<CS: CipherSuite>() -> TestVectorParameters {
     let client_login_start_result =
         ClientLogin::<CS>::start(&mut client_login_start_rng, password).unwrap();
     let credential_request_bytes = client_login_start_result.message.serialize().to_vec();
-    let client_login_state = client_login_start_result.state.serialize().to_vec();
+    let client_login_state = client_login_start_result
+        .state
+        .serialize()
+        .unwrap()
+        .to_vec();
 
     let mut server_e_sk_and_nonce_rng = CycleRng::new(
         [
@@ -594,7 +598,7 @@ fn test_credential_request() -> Result<(), ProtocolError> {
     );
     assert_eq!(
         hex::encode(&parameters.client_login_state),
-        hex::encode(client_login_start_result.state.serialize())
+        hex::encode(client_login_start_result.state.serialize()?)
     );
     Ok(())
 }
diff --git a/src/tests/voprf_test_vectors.rs b/src/tests/voprf_test_vectors.rs
index 1d8a449..f94f54f 100644
--- a/src/tests/voprf_test_vectors.rs
+++ b/src/tests/voprf_test_vectors.rs
@@ -63,7 +63,7 @@ fn populate_test_vectors(values: &Value) -> VOPRFTestVectorParameters {
 
 // Tests input -> blind, blinded_element
 #[test]
-fn test_blind() -> Result<(), PakeError> {
+fn test_blind() -> Result<(), ProtocolError> {
     for tv in OPRF_RISTRETTO255_SHA512 {
         let parameters = populate_test_vectors(&serde_json::from_str(tv).unwrap());
         let mut rng = CycleRng::new(parameters.blind.to_vec());
@@ -106,7 +106,7 @@ fn test_evaluate() -> Result<(), PakeError> {
 
 // Tests input, blind, evaluation_element -> output
 #[test]
-fn test_finalize() -> Result<(), PakeError> {
+fn test_finalize() -> Result<(), ProtocolError> {
     for tv in OPRF_RISTRETTO255_SHA512 {
         let parameters = populate_test_vectors(&serde_json::from_str(tv).unwrap());
 
@@ -116,7 +116,7 @@ fn test_finalize() -> Result<(), PakeError> {
             RistrettoPoint::from_element_slice(GenericArray::from_slice(
                 &parameters.evaluation_element,
             ))?,
-        );
+        )?;
 
         assert_eq!(&parameters.output, &output.to_vec());
     }