diff --git a/beacon_node/beacon_chain/src/beacon_chain.rs b/beacon_node/beacon_chain/src/beacon_chain.rs
index 01787f95b..816a570c0 100644
--- a/beacon_node/beacon_chain/src/beacon_chain.rs
+++ b/beacon_node/beacon_chain/src/beacon_chain.rs
@@ -82,7 +82,7 @@ where
         let state_root = genesis_state.canonical_root();
         state_store.put(&state_root, &ssz_encode(&genesis_state)[..])?;
 
-        let block_root = genesis_block.into_header().canonical_root();
+        let block_root = genesis_block.block_header().canonical_root();
         block_store.put(&block_root, &ssz_encode(&genesis_block)[..])?;
 
         let finalized_head = RwLock::new(CheckPoint::new(
@@ -189,7 +189,7 @@ where
     pub fn advance_state(&self, slot: Slot) -> Result<(), SlotProcessingError> {
         let state_slot = self.state.read().slot;
 
-        let latest_block_header = self.head().beacon_block.into_header();
+        let latest_block_header = self.head().beacon_block.block_header();
 
         for _ in state_slot.as_u64()..slot.as_u64() {
             per_slot_processing(&mut *self.state.write(), &latest_block_header, &self.spec)?;
@@ -561,7 +561,7 @@ where
     pub fn process_block(&self, block: BeaconBlock) -> Result<BlockProcessingOutcome, Error> {
         debug!("Processing block with slot {}...", block.slot);
 
-        let block_root = block.into_header().canonical_root();
+        let block_root = block.block_header().canonical_root();
 
         let present_slot = self.present_slot();
 
@@ -596,7 +596,7 @@ where
 
         // Transition the parent state to the present slot.
         let mut state = parent_state;
-        let previous_block_header = parent_block.into_header();
+        let previous_block_header = parent_block.block_header();
         for _ in state.slot.as_u64()..present_slot.as_u64() {
             if let Err(e) = per_slot_processing(&mut state, &previous_block_header, &self.spec) {
                 return Ok(BlockProcessingOutcome::InvalidBlock(
diff --git a/eth2/fork_choice/src/slow_lmd_ghost.rs b/eth2/fork_choice/src/slow_lmd_ghost.rs
index 25d137089..4b236cba4 100644
--- a/eth2/fork_choice/src/slow_lmd_ghost.rs
+++ b/eth2/fork_choice/src/slow_lmd_ghost.rs
@@ -215,10 +215,8 @@ impl<T: ClientDB + Sized> ForkChoice for SlowLMDGhost<T> {
                     head_vote_count = vote_count;
                 }
                 // resolve ties - choose smaller hash
-                else if vote_count == head_vote_count {
-                    if *child_hash < head_hash {
-                        head_hash = *child_hash;
-                    }
+                else if vote_count == head_vote_count && *child_hash < head_hash {
+                    head_hash = *child_hash;
                 }
             }
         }
diff --git a/eth2/state_processing/src/per_block_processing.rs b/eth2/state_processing/src/per_block_processing.rs
index 33f953b71..dc83abb3f 100644
--- a/eth2/state_processing/src/per_block_processing.rs
+++ b/eth2/state_processing/src/per_block_processing.rs
@@ -109,7 +109,7 @@ pub fn process_block_header(
         Invalid::ParentBlockRootMismatch
     );
 
-    state.latest_block_header = block.into_temporary_header(spec);
+    state.latest_block_header = block.temporary_block_header(spec);
 
     Ok(())
 }
@@ -388,7 +388,7 @@ pub fn process_deposits(
             // Create a new validator.
             let validator = Validator {
                 pubkey: deposit_input.pubkey.clone(),
-                withdrawal_credentials: deposit_input.withdrawal_credentials.clone(),
+                withdrawal_credentials: deposit_input.withdrawal_credentials,
                 activation_epoch: spec.far_future_epoch,
                 exit_epoch: spec.far_future_epoch,
                 withdrawable_epoch: spec.far_future_epoch,
diff --git a/eth2/state_processing/src/per_block_processing/validate_attestation.rs b/eth2/state_processing/src/per_block_processing/validate_attestation.rs
index 113dbc4ce..2143988a4 100644
--- a/eth2/state_processing/src/per_block_processing/validate_attestation.rs
+++ b/eth2/state_processing/src/per_block_processing/validate_attestation.rs
@@ -176,17 +176,7 @@ fn validate_attestation_signature_optional(
     );
 
     if verify_signature {
-        let attestation_epoch = attestation.data.slot.epoch(spec.slots_per_epoch);
-        verify_attestation_signature(
-            state,
-            committee,
-            attestation_epoch,
-            &attestation.aggregation_bitfield,
-            &attestation.custody_bitfield,
-            &attestation.data,
-            &attestation.aggregate_signature,
-            spec,
-        )?;
+        verify_attestation_signature(state, committee, attestation, spec)?;
     }
 
     // Crosslink data root is zero (to be removed in phase 1).
@@ -210,32 +200,29 @@ fn validate_attestation_signature_optional(
 fn verify_attestation_signature(
     state: &BeaconState,
     committee: &[usize],
-    attestation_epoch: Epoch,
-    aggregation_bitfield: &Bitfield,
-    custody_bitfield: &Bitfield,
-    attestation_data: &AttestationData,
-    aggregate_signature: &AggregateSignature,
+    a: &Attestation,
     spec: &ChainSpec,
 ) -> Result<(), Error> {
     let mut aggregate_pubs = vec![AggregatePublicKey::new(); 2];
     let mut message_exists = vec![false; 2];
+    let attestation_epoch = a.data.slot.epoch(spec.slots_per_epoch);
 
     for (i, v) in committee.iter().enumerate() {
-        let validator_signed = aggregation_bitfield.get(i).map_err(|_| {
+        let validator_signed = a.aggregation_bitfield.get(i).map_err(|_| {
             Error::Invalid(Invalid::BadAggregationBitfieldLength {
                 committee_len: committee.len(),
-                bitfield_len: aggregation_bitfield.len(),
+                bitfield_len: a.aggregation_bitfield.len(),
             })
         })?;
 
         if validator_signed {
-            let custody_bit: bool = match custody_bitfield.get(i) {
+            let custody_bit: bool = match a.custody_bitfield.get(i) {
                 Ok(bit) => bit,
                 // Invalidate signature if custody_bitfield.len() < committee
                 Err(_) => {
                     return Err(Error::Invalid(Invalid::BadCustodyBitfieldLength {
                         committee_len: committee.len(),
-                        bitfield_len: aggregation_bitfield.len(),
+                        bitfield_len: a.aggregation_bitfield.len(),
                     }));
                 }
             };
@@ -254,14 +241,14 @@ fn verify_attestation_signature(
 
     // Message when custody bitfield is `false`
     let message_0 = AttestationDataAndCustodyBit {
-        data: attestation_data.clone(),
+        data: a.data.clone(),
         custody_bit: false,
     }
     .hash_tree_root();
 
     // Message when custody bitfield is `true`
     let message_1 = AttestationDataAndCustodyBit {
-        data: attestation_data.clone(),
+        data: a.data.clone(),
         custody_bit: true,
     }
     .hash_tree_root();
@@ -283,7 +270,8 @@ fn verify_attestation_signature(
     let domain = spec.get_domain(attestation_epoch, Domain::Attestation, &state.fork);
 
     verify!(
-        aggregate_signature.verify_multiple(&messages[..], domain, &keys[..]),
+        a.aggregate_signature
+            .verify_multiple(&messages[..], domain, &keys[..]),
         Invalid::BadSignature
     );
 
diff --git a/eth2/state_processing/src/per_block_processing/verify_deposit.rs b/eth2/state_processing/src/per_block_processing/verify_deposit.rs
index 80d8bc24f..a3a0f5734 100644
--- a/eth2/state_processing/src/per_block_processing/verify_deposit.rs
+++ b/eth2/state_processing/src/per_block_processing/verify_deposit.rs
@@ -71,9 +71,7 @@ pub fn get_existing_validator_index(
 ) -> Result<Option<u64>, Error> {
     let deposit_input = &deposit.deposit_data.deposit_input;
 
-    let validator_index = state
-        .get_validator_index(&deposit_input.pubkey)?
-        .and_then(|i| Some(i));
+    let validator_index = state.get_validator_index(&deposit_input.pubkey)?;
 
     match validator_index {
         None => Ok(None),
diff --git a/eth2/state_processing/src/per_epoch_processing/get_attestation_participants.rs b/eth2/state_processing/src/per_epoch_processing/get_attestation_participants.rs
index 3e52776b1..52ba0274b 100644
--- a/eth2/state_processing/src/per_epoch_processing/get_attestation_participants.rs
+++ b/eth2/state_processing/src/per_epoch_processing/get_attestation_participants.rs
@@ -28,7 +28,7 @@ pub fn get_attestation_participants(
     let mut participants = Vec::with_capacity(committee.len());
     for (i, validator_index) in committee.iter().enumerate() {
         match bitfield.get(i) {
-            Ok(bit) if bit == true => participants.push(*validator_index),
+            Ok(bit) if bit => participants.push(*validator_index),
             _ => {}
         }
     }
diff --git a/eth2/state_processing/src/per_epoch_processing/update_registry_and_shuffling_data.rs b/eth2/state_processing/src/per_epoch_processing/update_registry_and_shuffling_data.rs
index 286ad8140..0b18c2571 100644
--- a/eth2/state_processing/src/per_epoch_processing/update_registry_and_shuffling_data.rs
+++ b/eth2/state_processing/src/per_epoch_processing/update_registry_and_shuffling_data.rs
@@ -64,7 +64,6 @@ pub fn should_update_validator_registry(
     let current_epoch_committee_count = spec.get_epoch_committee_count(num_active_validators);
 
     for shard in (0..current_epoch_committee_count)
-        .into_iter()
         .map(|i| (state.current_shuffling_start_shard + i as u64) % spec.shard_count)
     {
         if state.latest_crosslinks[shard as usize].epoch <= state.validator_registry_update_epoch {
diff --git a/eth2/types/src/beacon_block.rs b/eth2/types/src/beacon_block.rs
index b966751ed..6a3f1a354 100644
--- a/eth2/types/src/beacon_block.rs
+++ b/eth2/types/src/beacon_block.rs
@@ -71,7 +71,7 @@ impl BeaconBlock {
     /// Note: performs a full tree-hash of `self.body`.
     ///
     /// Spec v0.5.0
-    pub fn into_header(&self) -> BeaconBlockHeader {
+    pub fn block_header(&self) -> BeaconBlockHeader {
         BeaconBlockHeader {
             slot: self.slot,
             previous_block_root: self.previous_block_root,
@@ -84,11 +84,11 @@ impl BeaconBlock {
     /// Returns a "temporary" header, where the `state_root` is `spec.zero_hash`.
     ///
     /// Spec v0.5.0
-    pub fn into_temporary_header(&self, spec: &ChainSpec) -> BeaconBlockHeader {
+    pub fn temporary_block_header(&self, spec: &ChainSpec) -> BeaconBlockHeader {
         BeaconBlockHeader {
             state_root: spec.zero_hash,
             signature: spec.empty_signature.clone(),
-            ..self.into_header()
+            ..self.block_header()
         }
     }
 }
diff --git a/eth2/types/src/beacon_state.rs b/eth2/types/src/beacon_state.rs
index 1a165c9a9..1e5278124 100644
--- a/eth2/types/src/beacon_state.rs
+++ b/eth2/types/src/beacon_state.rs
@@ -162,7 +162,7 @@ impl BeaconState {
             latest_state_roots: vec![spec.zero_hash; spec.slots_per_historical_root],
             latest_active_index_roots: vec![spec.zero_hash; spec.latest_active_index_roots_length],
             latest_slashed_balances: vec![0; spec.latest_slashed_exit_length],
-            latest_block_header: BeaconBlock::empty(spec).into_temporary_header(spec),
+            latest_block_header: BeaconBlock::empty(spec).temporary_block_header(spec),
             historical_roots: vec![],
 
             /*
@@ -386,7 +386,8 @@ impl BeaconState {
         spec: &ChainSpec,
     ) -> Result<(), BeaconStateError> {
         let i = self.get_latest_block_roots_index(slot, spec)?;
-        Ok(self.latest_block_roots[i] = block_root)
+        self.latest_block_roots[i] = block_root;
+        Ok(())
     }
 
     /// Safely obtains the index for `latest_randao_mixes`
@@ -449,7 +450,8 @@ impl BeaconState {
         spec: &ChainSpec,
     ) -> Result<(), Error> {
         let i = self.get_randao_mix_index(epoch, spec)?;
-        Ok(self.latest_randao_mixes[i] = mix)
+        self.latest_randao_mixes[i] = mix;
+        Ok(())
     }
 
     /// Safely obtains the index for `latest_active_index_roots`, given some `epoch`.
@@ -492,7 +494,8 @@ impl BeaconState {
         spec: &ChainSpec,
     ) -> Result<(), Error> {
         let i = self.get_active_index_root_index(epoch, spec)?;
-        Ok(self.latest_active_index_roots[i] = index_root)
+        self.latest_active_index_roots[i] = index_root;
+        Ok(())
     }
 
     /// Replace `active_index_roots` with clones of `index_root`.
@@ -537,7 +540,8 @@ impl BeaconState {
         spec: &ChainSpec,
     ) -> Result<(), Error> {
         let i = self.get_latest_state_roots_index(slot, spec)?;
-        Ok(self.latest_state_roots[i] = state_root)
+        self.latest_state_roots[i] = state_root;
+        Ok(())
     }
 
     /// Safely obtains the index for `latest_slashed_balances`, given some `epoch`.
@@ -573,7 +577,8 @@ impl BeaconState {
         spec: &ChainSpec,
     ) -> Result<(), Error> {
         let i = self.get_slashed_balance_index(epoch, spec)?;
-        Ok(self.latest_slashed_balances[i] = balance)
+        self.latest_slashed_balances[i] = balance;
+        Ok(())
     }
 
     /// Generate a seed for the given `epoch`.
diff --git a/eth2/types/src/beacon_state/epoch_cache.rs b/eth2/types/src/beacon_state/epoch_cache.rs
index 6eebf1da3..32d9a643e 100644
--- a/eth2/types/src/beacon_state/epoch_cache.rs
+++ b/eth2/types/src/beacon_state/epoch_cache.rs
@@ -304,7 +304,6 @@ impl EpochCrosslinkCommitteesBuilder {
 
         for (i, slot) in self.epoch.slot_iter(spec.slots_per_epoch).enumerate() {
             for j in (0..committees.len())
-                .into_iter()
                 .skip(i * committees_per_slot)
                 .take(committees_per_slot)
             {
diff --git a/eth2/types/src/relative_epoch.rs b/eth2/types/src/relative_epoch.rs
index 6c135b1a6..8f895e97a 100644
--- a/eth2/types/src/relative_epoch.rs
+++ b/eth2/types/src/relative_epoch.rs
@@ -33,7 +33,7 @@ impl RelativeEpoch {
     /// Returns the `epoch` that `self` refers to, with respect to the `base` epoch.
     ///
     /// Spec v0.5.0
-    pub fn into_epoch(&self, base: Epoch) -> Epoch {
+    pub fn into_epoch(self, base: Epoch) -> Epoch {
         match self {
             RelativeEpoch::Previous => base - 1,
             RelativeEpoch::Current => base,
diff --git a/eth2/types/src/test_utils/testing_beacon_state_builder.rs b/eth2/types/src/test_utils/testing_beacon_state_builder.rs
index e76a01e49..6945769aa 100644
--- a/eth2/types/src/test_utils/testing_beacon_state_builder.rs
+++ b/eth2/types/src/test_utils/testing_beacon_state_builder.rs
@@ -214,7 +214,7 @@ impl TestingBeaconStateBuilder {
             - spec.min_attestation_inclusion_delay;
         let last_slot = std::cmp::min(state.slot.as_u64(), last_slot);
 
-        for slot in first_slot..last_slot + 1 {
+        for slot in first_slot..=last_slot {
             let slot = Slot::from(slot);
 
             let committees = state
diff --git a/eth2/types/src/test_utils/testing_deposit_builder.rs b/eth2/types/src/test_utils/testing_deposit_builder.rs
index ee258e7fe..326858c31 100644
--- a/eth2/types/src/test_utils/testing_deposit_builder.rs
+++ b/eth2/types/src/test_utils/testing_deposit_builder.rs
@@ -47,7 +47,7 @@ impl TestingDepositBuilder {
         self.deposit
             .deposit_data
             .deposit_input
-            .withdrawal_credentials = withdrawal_credentials.clone();
+            .withdrawal_credentials = withdrawal_credentials;
 
         self.deposit.deposit_data.deposit_input.proof_of_possession = self
             .deposit