diff --git a/beacon_node/beacon_chain/src/head_tracker.rs b/beacon_node/beacon_chain/src/head_tracker.rs
index 6d6ab6e12..4a4ce2fe5 100644
--- a/beacon_node/beacon_chain/src/head_tracker.rs
+++ b/beacon_node/beacon_chain/src/head_tracker.rs
@@ -1,7 +1,6 @@
 use parking_lot::RwLock;
 use ssz_derive::{Decode, Encode};
 use std::collections::HashMap;
-use std::iter::FromIterator;
 use types::{Hash256, Slot};
 
 #[derive(Debug, PartialEq)]
@@ -61,13 +60,12 @@ impl HeadTracker {
                 slots_len,
             })
         } else {
-            let map = HashMap::from_iter(
-                ssz_container
-                    .roots
-                    .iter()
-                    .zip(ssz_container.slots.iter())
-                    .map(|(root, slot)| (*root, *slot)),
-            );
+            let map = ssz_container
+                .roots
+                .iter()
+                .zip(ssz_container.slots.iter())
+                .map(|(root, slot)| (*root, *slot))
+                .collect::<HashMap<_, _>>();
 
             Ok(Self(RwLock::new(map)))
         }
diff --git a/beacon_node/beacon_chain/src/observed_operations.rs b/beacon_node/beacon_chain/src/observed_operations.rs
index e16ede5a0..f1eb996a5 100644
--- a/beacon_node/beacon_chain/src/observed_operations.rs
+++ b/beacon_node/beacon_chain/src/observed_operations.rs
@@ -2,7 +2,6 @@ use derivative::Derivative;
 use smallvec::SmallVec;
 use state_processing::{SigVerifiedOp, VerifyOperation};
 use std::collections::HashSet;
-use std::iter::FromIterator;
 use std::marker::PhantomData;
 use types::{
     AttesterSlashing, BeaconState, ChainSpec, EthSpec, ProposerSlashing, SignedVoluntaryExit,
@@ -57,10 +56,18 @@ impl<E: EthSpec> ObservableOperation<E> for ProposerSlashing {
 
 impl<E: EthSpec> ObservableOperation<E> for AttesterSlashing<E> {
     fn observed_validators(&self) -> SmallVec<[u64; SMALL_VEC_SIZE]> {
-        let attestation_1_indices =
-            HashSet::<u64>::from_iter(self.attestation_1.attesting_indices.iter().copied());
-        let attestation_2_indices =
-            HashSet::<u64>::from_iter(self.attestation_2.attesting_indices.iter().copied());
+        let attestation_1_indices = self
+            .attestation_1
+            .attesting_indices
+            .iter()
+            .copied()
+            .collect::<HashSet<u64>>();
+        let attestation_2_indices = self
+            .attestation_2
+            .attesting_indices
+            .iter()
+            .copied()
+            .collect::<HashSet<u64>>();
         attestation_1_indices
             .intersection(&attestation_2_indices)
             .copied()
diff --git a/beacon_node/eth1/src/service.rs b/beacon_node/eth1/src/service.rs
index 6cfbf581b..22c4600e0 100644
--- a/beacon_node/eth1/src/service.rs
+++ b/beacon_node/eth1/src/service.rs
@@ -878,7 +878,13 @@ impl Service {
                 // imported if any one of them cannot be parsed.
                 .collect::<Result<Vec<_>, _>>()?
                 .into_iter()
-                .map(|deposit_log| {
+                // Returns if a deposit is unable to be added to the cache.
+                //
+                // If this error occurs, the cache will no longer be guaranteed to hold either
+                // none or all of the logs for each block (i.e., they may exist _some_ logs for
+                // a block, but not _all_ logs for that block). This scenario can cause the
+                // node to choose an invalid genesis state or propose an invalid block.
+                .try_for_each(|deposit_log| {
                     if let DepositCacheInsertOutcome::Inserted = cache
                         .cache
                         .insert_log(deposit_log)
@@ -888,14 +894,7 @@ impl Service {
                     }
 
                     Ok(())
-                })
-                // Returns if a deposit is unable to be added to the cache.
-                //
-                // If this error occurs, the cache will no longer be guaranteed to hold either
-                // none or all of the logs for each block (i.e., they may exist _some_ logs for
-                // a block, but not _all_ logs for that block). This scenario can cause the
-                // node to choose an invalid genesis state or propose an invalid block.
-                .collect::<Result<_, _>>()?;
+                })?;
 
             debug!(
                 self.log,
diff --git a/beacon_node/eth2_libp2p/src/behaviour/gossipsub_scoring_parameters.rs b/beacon_node/eth2_libp2p/src/behaviour/gossipsub_scoring_parameters.rs
index 875c6cf84..54fc34f92 100644
--- a/beacon_node/eth2_libp2p/src/behaviour/gossipsub_scoring_parameters.rs
+++ b/beacon_node/eth2_libp2p/src/behaviour/gossipsub_scoring_parameters.rs
@@ -70,16 +70,16 @@ impl<TSpec: EthSpec> PeerScoreSettings<TSpec> {
         enr_fork_id: &EnrForkId,
         current_slot: Slot,
     ) -> error::Result<PeerScoreParams> {
-        let mut params = PeerScoreParams::default();
-
-        params.decay_interval = self.decay_interval;
-        params.decay_to_zero = self.decay_to_zero;
-        params.retain_score = self.epoch * 100;
-        params.app_specific_weight = 1.0;
-        params.ip_colocation_factor_threshold = 3.0;
-        params.behaviour_penalty_threshold = 6.0;
-
-        params.behaviour_penalty_decay = self.score_parameter_decay(self.epoch * 10);
+        let mut params = PeerScoreParams {
+            decay_interval: self.decay_interval,
+            decay_to_zero: self.decay_to_zero,
+            retain_score: self.epoch * 100,
+            app_specific_weight: 1.0,
+            ip_colocation_factor_threshold: 3.0,
+            behaviour_penalty_threshold: 6.0,
+            behaviour_penalty_decay: self.score_parameter_decay(self.epoch * 10),
+            ..Default::default()
+        };
 
         let target_value = Self::decay_convergence(
             params.behaviour_penalty_decay,
diff --git a/beacon_node/eth2_libp2p/src/peer_manager/peer_info.rs b/beacon_node/eth2_libp2p/src/peer_manager/peer_info.rs
index 92b39966c..3b95fc11a 100644
--- a/beacon_node/eth2_libp2p/src/peer_manager/peer_info.rs
+++ b/beacon_node/eth2_libp2p/src/peer_manager/peer_info.rs
@@ -97,7 +97,7 @@ impl<T: EthSpec> PeerInfo<T> {
     }
 
     /// Returns the seen IP addresses of the peer.
-    pub fn seen_addresses<'a>(&'a self) -> impl Iterator<Item = IpAddr> + 'a {
+    pub fn seen_addresses(&self) -> impl Iterator<Item = IpAddr> + '_ {
         self.seen_addresses
             .iter()
             .map(|socket_addr| socket_addr.ip())
diff --git a/beacon_node/eth2_libp2p/src/peer_manager/peer_sync_status.rs b/beacon_node/eth2_libp2p/src/peer_manager/peer_sync_status.rs
index 32580beff..473741d4f 100644
--- a/beacon_node/eth2_libp2p/src/peer_manager/peer_sync_status.rs
+++ b/beacon_node/eth2_libp2p/src/peer_manager/peer_sync_status.rs
@@ -29,14 +29,12 @@ pub struct SyncInfo {
 
 impl std::cmp::PartialEq for PeerSyncStatus {
     fn eq(&self, other: &Self) -> bool {
-        match (self, other) {
-            (PeerSyncStatus::Synced { .. }, PeerSyncStatus::Synced { .. }) => true,
-            (PeerSyncStatus::Advanced { .. }, PeerSyncStatus::Advanced { .. }) => true,
-            (PeerSyncStatus::Behind { .. }, PeerSyncStatus::Behind { .. }) => true,
-            (PeerSyncStatus::IrrelevantPeer, PeerSyncStatus::IrrelevantPeer) => true,
-            (PeerSyncStatus::Unknown, PeerSyncStatus::Unknown) => true,
-            _ => false,
-        }
+        matches!((self, other),
+            (PeerSyncStatus::Synced { .. }, PeerSyncStatus::Synced { .. }) |
+            (PeerSyncStatus::Advanced { .. }, PeerSyncStatus::Advanced { .. }) |
+            (PeerSyncStatus::Behind { .. }, PeerSyncStatus::Behind { .. }) |
+            (PeerSyncStatus::IrrelevantPeer, PeerSyncStatus::IrrelevantPeer) |
+            (PeerSyncStatus::Unknown, PeerSyncStatus::Unknown))
     }
 }
 
diff --git a/beacon_node/eth2_libp2p/src/types/sync_state.rs b/beacon_node/eth2_libp2p/src/types/sync_state.rs
index 628058abd..f5b6a1558 100644
--- a/beacon_node/eth2_libp2p/src/types/sync_state.rs
+++ b/beacon_node/eth2_libp2p/src/types/sync_state.rs
@@ -23,14 +23,12 @@ pub enum SyncState {
 
 impl PartialEq for SyncState {
     fn eq(&self, other: &Self) -> bool {
-        match (self, other) {
-            (SyncState::SyncingFinalized { .. }, SyncState::SyncingFinalized { .. }) => true,
-            (SyncState::SyncingHead { .. }, SyncState::SyncingHead { .. }) => true,
-            (SyncState::Synced, SyncState::Synced) => true,
-            (SyncState::Stalled, SyncState::Stalled) => true,
-            (SyncState::SyncTransition, SyncState::SyncTransition) => true,
-            _ => false,
-        }
+        matches!((self, other),
+            (SyncState::SyncingFinalized { .. }, SyncState::SyncingFinalized { .. }) |
+            (SyncState::SyncingHead { .. }, SyncState::SyncingHead { .. }) |
+            (SyncState::Synced, SyncState::Synced) |
+            (SyncState::Stalled, SyncState::Stalled) |
+            (SyncState::SyncTransition, SyncState::SyncTransition))
     }
 }
 
diff --git a/beacon_node/network/src/service/tests.rs b/beacon_node/network/src/service/tests.rs
index b425e1c64..c7186a839 100644
--- a/beacon_node/network/src/service/tests.rs
+++ b/beacon_node/network/src/service/tests.rs
@@ -70,11 +70,9 @@ mod tests {
             // Create a new network service which implicitly gets dropped at the
             // end of the block.
 
-            let _ = NetworkService::start(beacon_chain.clone(), &config, executor)
+            let _network_service = NetworkService::start(beacon_chain.clone(), &config, executor)
                 .await
                 .unwrap();
-            // Allow the network task to spawn on the executor before shutting down.
-            tokio::time::sleep(std::time::Duration::from_secs(1)).await;
             drop(signal);
         });
 
diff --git a/beacon_node/network/src/sync/range_sync/chain.rs b/beacon_node/network/src/sync/range_sync/chain.rs
index ccf18d2e5..01466e2a9 100644
--- a/beacon_node/network/src/sync/range_sync/chain.rs
+++ b/beacon_node/network/src/sync/range_sync/chain.rs
@@ -161,7 +161,7 @@ impl<T: BeaconChainTypes> SyncingChain<T> {
     }
 
     /// Peers currently syncing this chain.
-    pub fn peers<'a>(&'a self) -> impl Iterator<Item = PeerId> + 'a {
+    pub fn peers(&self) -> impl Iterator<Item = PeerId> + '_ {
         self.peers.keys().cloned()
     }
 
diff --git a/beacon_node/src/config.rs b/beacon_node/src/config.rs
index 437a94620..38df71c47 100644
--- a/beacon_node/src/config.rs
+++ b/beacon_node/src/config.rs
@@ -26,9 +26,10 @@ pub fn get_config<E: EthSpec>(
     spec: &ChainSpec,
     log: Logger,
 ) -> Result<ClientConfig, String> {
-    let mut client_config = ClientConfig::default();
-
-    client_config.data_dir = get_data_dir(cli_args);
+    let mut client_config = ClientConfig {
+        data_dir: get_data_dir(cli_args),
+        ..Default::default()
+    };
 
     // If necessary, remove any existing database and configuration
     if client_config.data_dir.exists() && cli_args.is_present("purge-db") {
diff --git a/beacon_node/store/src/hot_cold_store.rs b/beacon_node/store/src/hot_cold_store.rs
index a612d413e..31785bdf7 100644
--- a/beacon_node/store/src/hot_cold_store.rs
+++ b/beacon_node/store/src/hot_cold_store.rs
@@ -202,9 +202,7 @@ impl<E: EthSpec> HotColdDB<E, LevelDB<E>, LevelDB<E>> {
     }
 
     /// Return an iterator over the state roots of all temporary states.
-    pub fn iter_temporary_state_roots<'a>(
-        &'a self,
-    ) -> impl Iterator<Item = Result<Hash256, Error>> + 'a {
+    pub fn iter_temporary_state_roots(&self) -> impl Iterator<Item = Result<Hash256, Error>> + '_ {
         let column = DBColumn::BeaconStateTemporary;
         let start_key =
             BytesKey::from_vec(get_key_for_col(column.into(), Hash256::zero().as_bytes()));
diff --git a/common/account_utils/src/validator_definitions.rs b/common/account_utils/src/validator_definitions.rs
index 6106b4a5a..a38aebf40 100644
--- a/common/account_utils/src/validator_definitions.rs
+++ b/common/account_utils/src/validator_definitions.rs
@@ -12,7 +12,6 @@ use slog::{error, Logger};
 use std::collections::HashSet;
 use std::fs::{self, OpenOptions};
 use std::io;
-use std::iter::FromIterator;
 use std::path::{Path, PathBuf};
 use types::PublicKey;
 use validator_dir::VOTING_KEYSTORE_FILE;
@@ -154,13 +153,16 @@ impl ValidatorDefinitions {
         recursively_find_voting_keystores(validators_dir, &mut keystore_paths)
             .map_err(Error::UnableToSearchForKeystores)?;
 
-        let known_paths: HashSet<&PathBuf> =
-            HashSet::from_iter(self.0.iter().map(|def| match &def.signing_definition {
+        let known_paths: HashSet<&PathBuf> = self
+            .0
+            .iter()
+            .map(|def| match &def.signing_definition {
                 SigningDefinition::LocalKeystore {
                     voting_keystore_path,
                     ..
                 } => voting_keystore_path,
-            }));
+            })
+            .collect();
 
         let mut new_defs = keystore_paths
             .into_iter()
diff --git a/common/eth2/src/types.rs b/common/eth2/src/types.rs
index 41e705c72..49719a4c2 100644
--- a/common/eth2/src/types.rs
+++ b/common/eth2/src/types.rs
@@ -449,7 +449,7 @@ impl<T: FromStr> TryFrom<String> for QueryVec<T> {
     type Error = String;
 
     fn try_from(string: String) -> Result<Self, Self::Error> {
-        if string == "" {
+        if string.is_empty() {
             return Ok(Self(vec![]));
         }
 
diff --git a/consensus/cached_tree_hash/src/impls.rs b/consensus/cached_tree_hash/src/impls.rs
index 6c7e3cf41..0e6bf6142 100644
--- a/consensus/cached_tree_hash/src/impls.rs
+++ b/consensus/cached_tree_hash/src/impls.rs
@@ -24,15 +24,15 @@ pub fn u64_leaf_count(len: usize) -> usize {
     (len + vals_per_chunk - 1) / vals_per_chunk
 }
 
-pub fn hash256_iter<'a>(
-    values: &'a [Hash256],
-) -> impl Iterator<Item = [u8; BYTES_PER_CHUNK]> + ExactSizeIterator + 'a {
+pub fn hash256_iter(
+    values: &[Hash256],
+) -> impl Iterator<Item = [u8; BYTES_PER_CHUNK]> + ExactSizeIterator + '_ {
     values.iter().copied().map(Hash256::to_fixed_bytes)
 }
 
-pub fn u64_iter<'a>(
-    values: &'a [u64],
-) -> impl Iterator<Item = [u8; BYTES_PER_CHUNK]> + ExactSizeIterator + 'a {
+pub fn u64_iter(
+    values: &[u64],
+) -> impl Iterator<Item = [u8; BYTES_PER_CHUNK]> + ExactSizeIterator + '_ {
     let type_size = size_of::<u64>();
     let vals_per_chunk = BYTES_PER_CHUNK / type_size;
     values.chunks(vals_per_chunk).map(move |xs| {
diff --git a/consensus/proto_array/src/ssz_container.rs b/consensus/proto_array/src/ssz_container.rs
index 06dc48c5f..c79c433e3 100644
--- a/consensus/proto_array/src/ssz_container.rs
+++ b/consensus/proto_array/src/ssz_container.rs
@@ -4,7 +4,6 @@ use crate::{
 };
 use ssz_derive::{Decode, Encode};
 use std::collections::HashMap;
-use std::iter::FromIterator;
 use types::{Epoch, Hash256};
 
 #[derive(Encode, Decode)]
@@ -41,7 +40,7 @@ impl From<SszContainer> for ProtoArrayForkChoice {
             justified_epoch: from.justified_epoch,
             finalized_epoch: from.finalized_epoch,
             nodes: from.nodes,
-            indices: HashMap::from_iter(from.indices.into_iter()),
+            indices: from.indices.into_iter().collect::<HashMap<_, _>>(),
         };
 
         Self {
diff --git a/consensus/ssz_derive/src/lib.rs b/consensus/ssz_derive/src/lib.rs
index cee167012..2170251ae 100644
--- a/consensus/ssz_derive/src/lib.rs
+++ b/consensus/ssz_derive/src/lib.rs
@@ -14,9 +14,7 @@ use syn::{parse_macro_input, DeriveInput};
 ///
 /// # Panics
 /// Any unnamed struct field (like in a tuple struct) will raise a panic at compile time.
-fn get_serializable_named_field_idents<'a>(
-    struct_data: &'a syn::DataStruct,
-) -> Vec<&'a syn::Ident> {
+fn get_serializable_named_field_idents(struct_data: &syn::DataStruct) -> Vec<&syn::Ident> {
     struct_data
         .fields
         .iter()
@@ -35,7 +33,7 @@ fn get_serializable_named_field_idents<'a>(
 
 /// Returns a Vec of `syn::Type` for each named field in the struct, whilst filtering out fields
 /// that should not be serialized.
-fn get_serializable_field_types<'a>(struct_data: &'a syn::DataStruct) -> Vec<&'a syn::Type> {
+fn get_serializable_field_types(struct_data: &syn::DataStruct) -> Vec<&syn::Type> {
     struct_data
         .fields
         .iter()
diff --git a/consensus/state_processing/src/per_block_processing/signature_sets.rs b/consensus/state_processing/src/per_block_processing/signature_sets.rs
index e6b71b24e..cac8c4d1c 100644
--- a/consensus/state_processing/src/per_block_processing/signature_sets.rs
+++ b/consensus/state_processing/src/per_block_processing/signature_sets.rs
@@ -44,10 +44,10 @@ impl From<BeaconStateError> for Error {
 }
 
 /// Helper function to get a public key from a `state`.
-pub fn get_pubkey_from_state<'a, T>(
-    state: &'a BeaconState<T>,
+pub fn get_pubkey_from_state<T>(
+    state: &BeaconState<T>,
     validator_index: usize,
-) -> Option<Cow<'a, PublicKey>>
+) -> Option<Cow<PublicKey>>
 where
     T: EthSpec,
 {
diff --git a/consensus/state_processing/src/per_block_processing/tests.rs b/consensus/state_processing/src/per_block_processing/tests.rs
index 55bc459cd..a0dcd66c4 100644
--- a/consensus/state_processing/src/per_block_processing/tests.rs
+++ b/consensus/state_processing/src/per_block_processing/tests.rs
@@ -391,7 +391,7 @@ fn invalid_attestation_wrong_justified_checkpoint() {
                     root: Hash256::zero(),
                 },
                 attestation: Checkpoint {
-                    epoch: Epoch::from(0 as u64),
+                    epoch: Epoch::from(0_u64),
                     root: Hash256::zero(),
                 },
                 is_current: true,
@@ -877,7 +877,7 @@ fn invalid_proposer_slashing_proposal_epoch_mismatch() {
         Err(BlockProcessingError::ProposerSlashingInvalid {
             index: 0,
             reason: ProposerSlashingInvalid::ProposalSlotMismatch(
-                Slot::from(0 as u64),
+                Slot::from(0_u64),
                 Slot::from(128 as u64)
             )
         })
diff --git a/consensus/tree_hash_derive/src/lib.rs b/consensus/tree_hash_derive/src/lib.rs
index d57903654..97a332394 100644
--- a/consensus/tree_hash_derive/src/lib.rs
+++ b/consensus/tree_hash_derive/src/lib.rs
@@ -10,7 +10,7 @@ use syn::{parse_macro_input, Attribute, DeriveInput, Meta};
 ///
 /// # Panics
 /// Any unnamed struct field (like in a tuple struct) will raise a panic at compile time.
-fn get_hashable_fields<'a>(struct_data: &'a syn::DataStruct) -> Vec<&'a syn::Ident> {
+fn get_hashable_fields(struct_data: &syn::DataStruct) -> Vec<&syn::Ident> {
     get_hashable_fields_and_their_caches(struct_data)
         .into_iter()
         .map(|(ident, _, _)| ident)
@@ -18,9 +18,9 @@ fn get_hashable_fields<'a>(struct_data: &'a syn::DataStruct) -> Vec<&'a syn::Ide
 }
 
 /// Return a Vec of the hashable fields of a struct, and each field's type and optional cache field.
-fn get_hashable_fields_and_their_caches<'a>(
-    struct_data: &'a syn::DataStruct,
-) -> Vec<(&'a syn::Ident, syn::Type, Option<syn::Ident>)> {
+fn get_hashable_fields_and_their_caches(
+    struct_data: &syn::DataStruct,
+) -> Vec<(&syn::Ident, syn::Type, Option<syn::Ident>)> {
     struct_data
         .fields
         .iter()
diff --git a/consensus/types/src/beacon_block.rs b/consensus/types/src/beacon_block.rs
index d3a916070..71b0f9545 100644
--- a/consensus/types/src/beacon_block.rs
+++ b/consensus/types/src/beacon_block.rs
@@ -68,7 +68,7 @@ impl<T: EthSpec> BeaconBlock<T> {
         };
         let indexed_attestation: IndexedAttestation<T> = IndexedAttestation {
             attesting_indices: VariableList::new(vec![
-                0 as u64;
+                0_u64;
                 T::MaxValidatorsPerCommittee::to_usize()
             ])
             .unwrap(),
diff --git a/consensus/types/src/test_utils/builders/testing_attestation_data_builder.rs b/consensus/types/src/test_utils/builders/testing_attestation_data_builder.rs
index 56b3e3bbe..a704374ee 100644
--- a/consensus/types/src/test_utils/builders/testing_attestation_data_builder.rs
+++ b/consensus/types/src/test_utils/builders/testing_attestation_data_builder.rs
@@ -69,7 +69,7 @@ impl TestingAttestationDataBuilder {
             }
             AttestationTestTask::WrongJustifiedCheckpoint => {
                 source = Checkpoint {
-                    epoch: Epoch::from(0 as u64),
+                    epoch: Epoch::from(0_u64),
                     root: Hash256::zero(),
                 }
             }
diff --git a/crypto/eth2_key_derivation/src/derived_key.rs b/crypto/eth2_key_derivation/src/derived_key.rs
index 8ed6c9bd4..a783a511d 100644
--- a/crypto/eth2_key_derivation/src/derived_key.rs
+++ b/crypto/eth2_key_derivation/src/derived_key.rs
@@ -35,6 +35,11 @@ pub const MOD_R_L: usize = 48;
 #[zeroize(drop)]
 pub struct DerivedKey(ZeroizeHash);
 
+#[derive(Debug, PartialEq)]
+pub enum Error {
+    EmptySeed,
+}
+
 impl DerivedKey {
     /// Instantiates `Self` from some secret seed bytes.
     ///
@@ -42,10 +47,10 @@ impl DerivedKey {
     ///
     /// ## Errors
     ///
-    /// Returns `Err(())` if `seed.is_empty()`, otherwise always returns `Ok(self)`.
-    pub fn from_seed(seed: &[u8]) -> Result<Self, ()> {
+    /// Returns `Err(Error::EmptySeed)` if `seed.is_empty()`, otherwise always returns `Ok(self)`.
+    pub fn from_seed(seed: &[u8]) -> Result<Self, Error> {
         if seed.is_empty() {
-            Err(())
+            Err(Error::EmptySeed)
         } else {
             Ok(Self(derive_master_sk(seed)))
         }
diff --git a/crypto/eth2_key_derivation/src/lib.rs b/crypto/eth2_key_derivation/src/lib.rs
index 8c5c1c519..aa29da6b8 100644
--- a/crypto/eth2_key_derivation/src/lib.rs
+++ b/crypto/eth2_key_derivation/src/lib.rs
@@ -8,4 +8,5 @@ mod secret_bytes;
 
 pub use bls::ZeroizeHash;
 pub use derived_key::DerivedKey;
+pub use derived_key::Error as DerivedKeyError;
 pub use plain_text::PlainText;
diff --git a/crypto/eth2_wallet/src/wallet.rs b/crypto/eth2_wallet/src/wallet.rs
index 694be44d4..a03e63557 100644
--- a/crypto/eth2_wallet/src/wallet.rs
+++ b/crypto/eth2_wallet/src/wallet.rs
@@ -5,17 +5,16 @@ use crate::{
     },
     KeyType, ValidatorPath,
 };
+pub use bip39::{Mnemonic, Seed as Bip39Seed};
+pub use eth2_key_derivation::{DerivedKey, DerivedKeyError};
 use eth2_keystore::{
     decrypt, default_kdf, encrypt, keypair_from_secret, Keystore, KeystoreBuilder, IV_SIZE,
     SALT_SIZE,
 };
+pub use eth2_keystore::{Error as KeystoreError, PlainText};
 use rand::prelude::*;
 use serde::{Deserialize, Serialize};
 use std::io::{Read, Write};
-
-pub use bip39::{Mnemonic, Seed as Bip39Seed};
-pub use eth2_key_derivation::DerivedKey;
-pub use eth2_keystore::{Error as KeystoreError, PlainText};
 pub use uuid::Uuid;
 
 #[derive(Debug, PartialEq)]
@@ -24,6 +23,7 @@ pub enum Error {
     PathExhausted,
     EmptyPassword,
     EmptySeed,
+    InvalidNextAccount { old: u32, new: u32 },
 }
 
 impl From<KeystoreError> for Error {
@@ -32,6 +32,14 @@ impl From<KeystoreError> for Error {
     }
 }
 
+impl From<DerivedKeyError> for Error {
+    fn from(e: DerivedKeyError) -> Error {
+        match e {
+            DerivedKeyError::EmptySeed => Error::EmptySeed,
+        }
+    }
+}
+
 /// Contains the two keystores required for an eth2 validator.
 pub struct ValidatorKeystores {
     /// Contains the secret key used for signing every-day consensus messages (blocks,
@@ -222,12 +230,15 @@ impl Wallet {
     ///
     /// Returns `Err(())` if `nextaccount` is less than `self.nextaccount()` without mutating
     /// `self`. This is to protect against duplicate validator generation.
-    pub fn set_nextaccount(&mut self, nextaccount: u32) -> Result<(), ()> {
+    pub fn set_nextaccount(&mut self, nextaccount: u32) -> Result<(), Error> {
         if nextaccount >= self.nextaccount() {
             self.json.nextaccount = nextaccount;
             Ok(())
         } else {
-            Err(())
+            Err(Error::InvalidNextAccount {
+                old: self.json.nextaccount,
+                new: nextaccount,
+            })
         }
     }
 
@@ -295,7 +306,7 @@ pub fn recover_validator_secret(
 ) -> Result<(PlainText, ValidatorPath), Error> {
     let path = ValidatorPath::new(index, key_type);
     let secret = wallet.decrypt_seed(wallet_password)?;
-    let master = DerivedKey::from_seed(secret.as_bytes()).map_err(|()| Error::EmptyPassword)?;
+    let master = DerivedKey::from_seed(secret.as_bytes()).map_err(Error::from)?;
 
     let destination = path.iter_nodes().fold(master, |dk, i| dk.child(*i));
 
@@ -311,7 +322,7 @@ pub fn recover_validator_secret_from_mnemonic(
     key_type: KeyType,
 ) -> Result<(PlainText, ValidatorPath), Error> {
     let path = ValidatorPath::new(index, key_type);
-    let master = DerivedKey::from_seed(secret).map_err(|()| Error::EmptyPassword)?;
+    let master = DerivedKey::from_seed(secret).map_err(Error::from)?;
 
     let destination = path.iter_nodes().fold(master, |dk, i| dk.child(*i));
 
diff --git a/lcli/src/generate_bootnode_enr.rs b/lcli/src/generate_bootnode_enr.rs
index da79a1fa2..e2eace268 100644
--- a/lcli/src/generate_bootnode_enr.rs
+++ b/lcli/src/generate_bootnode_enr.rs
@@ -25,10 +25,12 @@ pub fn run<T: EthSpec>(matches: &ArgMatches) -> Result<(), String> {
         ));
     }
 
-    let mut config = NetworkConfig::default();
-    config.enr_address = Some(ip);
-    config.enr_udp_port = Some(udp_port);
-    config.enr_tcp_port = Some(tcp_port);
+    let config = NetworkConfig {
+        enr_address: Some(ip),
+        enr_udp_port: Some(udp_port),
+        enr_tcp_port: Some(tcp_port),
+        ..Default::default()
+    };
 
     let local_keypair = Keypair::generate_secp256k1();
     let enr_key = CombinedKey::from_libp2p(&local_keypair)?;
diff --git a/slasher/src/test_utils.rs b/slasher/src/test_utils.rs
index bd3b06c52..46ce23da5 100644
--- a/slasher/src/test_utils.rs
+++ b/slasher/src/test_utils.rs
@@ -1,7 +1,6 @@
 use slog::Logger;
 use sloggers::Build;
 use std::collections::HashSet;
-use std::iter::FromIterator;
 use types::{
     AggregateSignature, AttestationData, AttesterSlashing, BeaconBlockHeader, Checkpoint, Epoch,
     Hash256, IndexedAttestation, MainnetEthSpec, Signature, SignedBeaconBlockHeader, Slot,
@@ -59,8 +58,14 @@ pub fn hashset_intersection(
     attestation_1_indices: &[u64],
     attestation_2_indices: &[u64],
 ) -> HashSet<u64> {
-    &HashSet::from_iter(attestation_1_indices.iter().copied())
-        & &HashSet::from_iter(attestation_2_indices.iter().copied())
+    &attestation_1_indices
+        .iter()
+        .copied()
+        .collect::<HashSet<u64>>()
+        & &attestation_2_indices
+            .iter()
+            .copied()
+            .collect::<HashSet<u64>>()
 }
 
 pub fn slashed_validators_from_slashings(slashings: &HashSet<AttesterSlashing<E>>) -> HashSet<u64> {
diff --git a/testing/remote_signer_test/src/utils.rs b/testing/remote_signer_test/src/utils.rs
index 6b9586b36..858f4d602 100644
--- a/testing/remote_signer_test/src/utils.rs
+++ b/testing/remote_signer_test/src/utils.rs
@@ -102,11 +102,8 @@ pub fn get_block<E: EthSpec>(seed: u64) -> BeaconBlock<E> {
         signature: Signature::empty(),
     };
     let indexed_attestation: IndexedAttestation<E> = IndexedAttestation {
-        attesting_indices: VariableList::new(vec![
-            0 as u64;
-            E::MaxValidatorsPerCommittee::to_usize()
-        ])
-        .unwrap(),
+        attesting_indices: VariableList::new(vec![0_u64; E::MaxValidatorsPerCommittee::to_usize()])
+            .unwrap(),
         data: AttestationData::default(),
         signature: AggregateSignature::empty(),
     };
diff --git a/validator_client/slashing_protection/src/interchange.rs b/validator_client/slashing_protection/src/interchange.rs
index 542807d0d..1a73f6d00 100644
--- a/validator_client/slashing_protection/src/interchange.rs
+++ b/validator_client/slashing_protection/src/interchange.rs
@@ -1,6 +1,5 @@
 use serde_derive::{Deserialize, Serialize};
 use std::collections::HashSet;
-use std::iter::FromIterator;
 use types::{Epoch, Hash256, PublicKey, Slot};
 
 #[derive(Debug, Clone, PartialEq, Deserialize, Serialize)]
@@ -60,8 +59,8 @@ impl Interchange {
 
     /// Do these two `Interchange`s contain the same data (ignoring ordering)?
     pub fn equiv(&self, other: &Self) -> bool {
-        let self_set = HashSet::<_>::from_iter(self.data.iter());
-        let other_set = HashSet::<_>::from_iter(other.data.iter());
+        let self_set = self.data.iter().collect::<HashSet<_>>();
+        let other_set = other.data.iter().collect::<HashSet<_>>();
         self.metadata == other.metadata && self_set == other_set
     }
 
diff --git a/validator_client/src/http_api/create_validator.rs b/validator_client/src/http_api/create_validator.rs
index bc4f21561..2834a1839 100644
--- a/validator_client/src/http_api/create_validator.rs
+++ b/validator_client/src/http_api/create_validator.rs
@@ -43,8 +43,11 @@ pub async fn create_validators<P: AsRef<Path>, T: 'static + SlotClock, E: EthSpe
             })?;
 
     if let Some(nextaccount) = key_derivation_path_offset {
-        wallet.set_nextaccount(nextaccount).map_err(|()| {
-            warp_utils::reject::custom_server_error("unable to set wallet nextaccount".to_string())
+        wallet.set_nextaccount(nextaccount).map_err(|e| {
+            warp_utils::reject::custom_server_error(format!(
+                "unable to set wallet nextaccount: {:?}",
+                e
+            ))
         })?;
     }