diff --git a/src/account_diff.rs b/src/account_diff.rs
index 05c4d00a6..fece8c5d7 100644
--- a/src/account_diff.rs
+++ b/src/account_diff.rs
@@ -66,7 +66,7 @@ impl AccountDiff {
 							post.storage.get(&k).cloned().unwrap_or(H256::new())
 						))).collect(),
 				};
-				if r.balance.is_same() && r.nonce.is_same() && r.code.is_same() && r.storage.len() == 0 {
+				if r.balance.is_same() && r.nonce.is_same() && r.code.is_same() && r.storage.is_empty() {
 					None
 				} else {
 					Some(r)
diff --git a/src/block.rs b/src/block.rs
index e5ca18e8c..eacf30b44 100644
--- a/src/block.rs
+++ b/src/block.rs
@@ -1,3 +1,5 @@
+#![allow(ptr_arg)] // Because of &LastHashes -> &Vec<_>
+
 use common::*;
 use engine::*;
 use state::*;
@@ -169,7 +171,7 @@ impl<'x, 'y> OpenBlock<'x, 'y> {
 			timestamp: self.block.header.timestamp,
 			difficulty: self.block.header.difficulty.clone(),
 			last_hashes: self.last_hashes.clone(),		// TODO: should be a reference.
-			gas_used: self.block.archive.last().map(|t| t.receipt.gas_used).unwrap_or(U256::from(0)),
+			gas_used: self.block.archive.last().map_or(U256::zero(), |t| t.receipt.gas_used),
 			gas_limit: self.block.header.gas_limit.clone(),
 		}
 	}
@@ -200,7 +202,7 @@ impl<'x, 'y> OpenBlock<'x, 'y> {
 		s.block.header.state_root = s.block.state.root().clone();
 		s.block.header.receipts_root = ordered_trie_root(s.block.archive.iter().map(|ref e| e.receipt.rlp_bytes()).collect());
 		s.block.header.log_bloom = s.block.archive.iter().fold(LogBloom::zero(), |mut b, e| {b |= &e.receipt.log_bloom; b});
-		s.block.header.gas_used = s.block.archive.last().map(|t| t.receipt.gas_used).unwrap_or(U256::from(0));
+		s.block.header.gas_used = s.block.archive.last().map_or(U256::zero(), |t| t.receipt.gas_used);
 		s.block.header.note_dirty();
 
 		ClosedBlock::new(s, uncle_bytes)
@@ -251,7 +253,7 @@ impl SealedBlock {
 		let mut block_rlp = RlpStream::new_list(3);
 		self.block.header.stream_rlp(&mut block_rlp, Seal::With);
 		block_rlp.append_list(self.block.archive.len());
-		for e in self.block.archive.iter() { e.transaction.rlp_append(&mut block_rlp); }
+		for e in &self.block.archive { e.transaction.rlp_append(&mut block_rlp); }
 		block_rlp.append_raw(&self.uncle_bytes, 1);
 		block_rlp.out()
 	}
diff --git a/src/blockchain.rs b/src/blockchain.rs
index 3c44e8354..2f1bebf48 100644
--- a/src/blockchain.rs
+++ b/src/blockchain.rs
@@ -490,9 +490,8 @@ impl BlockChain {
 		K: ExtrasSliceConvertable + Eq + Hash + Clone {
 		{
 			let read = cache.read().unwrap();
-			match read.get(hash) {
-				Some(v) => return Some(v.clone()),
-				None => ()
+			if let Some(v) = read.get(hash) {
+				return Some(v.clone());
 			}
 		}
 
diff --git a/src/ethereum/ethash.rs b/src/ethereum/ethash.rs
index 8a86cf4e5..6ab49c1ac 100644
--- a/src/ethereum/ethash.rs
+++ b/src/ethereum/ethash.rs
@@ -31,13 +31,13 @@ impl Ethash {
 	}
 
 	fn u64_param(&self, name: &str) -> u64 {
-		*self.u64_params.write().unwrap().entry(name.to_string()).or_insert_with(||
-			self.spec().engine_params.get(name).map(|a| decode(&a)).unwrap_or(0u64))
+		*self.u64_params.write().unwrap().entry(name.to_owned()).or_insert_with(||
+			self.spec().engine_params.get(name).map_or(0u64, |a| decode(&a)))
 	}
 
 	fn u256_param(&self, name: &str) -> U256 {
-		*self.u256_params.write().unwrap().entry(name.to_string()).or_insert_with(||
-			self.spec().engine_params.get(name).map(|a| decode(&a)).unwrap_or(x!(0)))
+		*self.u256_params.write().unwrap().entry(name.to_owned()).or_insert_with(||
+			self.spec().engine_params.get(name).map_or(x!(0), |a| decode(&a)))
 	}
 }
 
@@ -83,7 +83,7 @@ impl Engine for Ethash {
 	/// Apply the block reward on finalisation of the block.
 	/// This assumes that all uncles are valid uncles (i.e. of at least one generation before the current).
 	fn on_close_block(&self, block: &mut Block) {
-		let reward = self.spec().engine_params.get("blockReward").map(|a| decode(&a)).unwrap_or(U256::from(0u64));
+		let reward = self.spec().engine_params.get("blockReward").map_or(U256::from(0u64), |a| decode(&a));
 		let fields = block.fields();
 
 		// Bestow block reward
diff --git a/src/evm/factory.rs b/src/evm/factory.rs
index 3dde4bb6d..5b4d545ac 100644
--- a/src/evm/factory.rs
+++ b/src/evm/factory.rs
@@ -65,10 +65,11 @@ impl Factory {
 	fn jit() -> Box<Evm> {
 		unimplemented!()
 	}
-
+}
+impl Default for Factory {
 	/// Returns jitvm factory
 	#[cfg(feature = "jit")]
-	pub fn default() -> Factory {
+	fn default() -> Factory {
 		Factory {
 			evm: VMType::Jit
 		}
@@ -76,7 +77,7 @@ impl Factory {
 
 	/// Returns native rust evm factory
 	#[cfg(not(feature = "jit"))]
-	pub fn default() -> Factory {
+	fn default() -> Factory {
 		Factory {
 			evm: VMType::Interpreter
 		}
diff --git a/src/evm/interpreter.rs b/src/evm/interpreter.rs
index 0fd546b34..dc382e90e 100644
--- a/src/evm/interpreter.rs
+++ b/src/evm/interpreter.rs
@@ -229,6 +229,7 @@ struct CodeReader<'a> {
 	code: &'a Bytes
 }
 
+#[allow(len_without_is_empty)]
 impl<'a> CodeReader<'a> {
 	/// Get `no_of_bytes` from code and convert to U256. Move PC
 	fn read(&mut self, no_of_bytes: usize) -> U256 {
@@ -331,6 +332,7 @@ impl evm::Evm for Interpreter {
 }
 
 impl Interpreter {
+	#[allow(cyclomatic_complexity)]
 	fn get_gas_cost_mem(&self,
 						ext: &evm::Ext,
 						instruction: Instruction,
diff --git a/src/lib.rs b/src/lib.rs
index 8ae81fbf2..14626a62f 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -3,6 +3,8 @@
 #![feature(wrapping)]
 //#![feature(plugin)]
 //#![plugin(interpolate_idents)]
+#![allow(match_bool, needless_range_loop, match_ref_pats)]
+
 //! Ethcore's ethereum implementation
 //!
 //! ### Rust version
@@ -86,7 +88,6 @@ extern crate num_cpus;
 #[cfg(feature = "jit" )]
 extern crate evmjit;
 #[macro_use]
-#[allow(match_bool)]
 extern crate ethcore_util as util;
 
 pub mod common;
diff --git a/src/spec.rs b/src/spec.rs
index 210b46dca..363fd9a49 100644
--- a/src/spec.rs
+++ b/src/spec.rs
@@ -200,7 +200,7 @@ impl FromJson for Spec {
 
 		
 		Spec {
-			name: json.find("name").map(|j| j.as_string().unwrap()).unwrap_or("unknown").to_owned(),
+			name: json.find("name").map_or("unknown", |j| j.as_string().unwrap()).to_owned(),
 			engine_name: json["engineName"].as_string().unwrap().to_owned(),
 			engine_params: json_to_rlp_map(&json["params"]),
 			builtins: builtins,
diff --git a/src/sync/chain.rs b/src/sync/chain.rs
index 795ed4f0e..e95e51ba2 100644
--- a/src/sync/chain.rs
+++ b/src/sync/chain.rs
@@ -268,6 +268,7 @@ impl ChainSync {
 		Ok(())
 	}
 
+	#[allow(cyclomatic_complexity)]
 	/// Called by peer once it has new block headers during sync
 	fn on_peer_block_headers(&mut self, io: &mut SyncIo, peer_id: PeerId, r: &UntrustedRlp) -> Result<(), PacketDecodeError> {
 		self.reset_peer_asking(peer_id, PeerAsking::BlockHeaders);
@@ -865,12 +866,9 @@ impl ChainSync {
 		let mut added = 0usize;
 		let mut data = Bytes::new();
 		for i in 0..count {
-			match io.chain().block_body(&try!(r.val_at::<H256>(i))) {
-				Some(mut hdr) => {
-					data.append(&mut hdr);
-					added += 1;
-				}
-				None => {}
+			if let Some(mut hdr) = io.chain().block_body(&try!(r.val_at::<H256>(i))) {
+				data.append(&mut hdr);
+				added += 1;
 			}
 		}
 		let mut rlp = RlpStream::new_list(added);
@@ -892,12 +890,9 @@ impl ChainSync {
 		let mut added = 0usize;
 		let mut data = Bytes::new();
 		for i in 0..count {
-			match io.chain().state_data(&try!(r.val_at::<H256>(i))) {
-				Some(mut hdr) => {
-					data.append(&mut hdr);
-					added += 1;
-				}
-				None => {}
+			if let Some(mut hdr) = io.chain().state_data(&try!(r.val_at::<H256>(i))) {
+				data.append(&mut hdr);
+				added += 1;
 			}
 		}
 		let mut rlp = RlpStream::new_list(added);
@@ -918,12 +913,9 @@ impl ChainSync {
 		let mut added = 0usize;
 		let mut data = Bytes::new();
 		for i in 0..count {
-			match io.chain().block_receipts(&try!(r.val_at::<H256>(i))) {
-				Some(mut hdr) => {
-					data.append(&mut hdr);
-					added += 1;
-				}
-				None => {}
+			if let Some(mut hdr) = io.chain().block_receipts(&try!(r.val_at::<H256>(i))) {
+				data.append(&mut hdr);
+				added += 1;
 			}
 		}
 		let mut rlp = RlpStream::new_list(added);
diff --git a/src/sync/io.rs b/src/sync/io.rs
index affcbc0d7..aa572c133 100644
--- a/src/sync/io.rs
+++ b/src/sync/io.rs
@@ -14,7 +14,7 @@ pub trait SyncIo {
 	/// Send a packet to a peer.
 	fn send(&mut self, peer_id: PeerId, packet_id: PacketId, data: Vec<u8>) -> Result<(), UtilError>;
 	/// Get the blockchain
-	fn chain<'s>(&'s mut self) -> &'s mut BlockChainClient;
+	fn chain(&mut self) -> &mut BlockChainClient;
 	/// Returns peer client identifier string
 	fn peer_info(&self, peer_id: PeerId) -> String {
 		peer_id.to_string()
@@ -50,7 +50,7 @@ impl<'s, 'h, 'op> SyncIo for NetSyncIo<'s, 'h, 'op> {
 		self.network.send(peer_id, packet_id, data)
 	}
 
-	fn chain<'a>(&'a mut self) -> &'a mut BlockChainClient {
+	fn chain(&mut self) -> &mut BlockChainClient {
 		self.chain
 	}
 
diff --git a/src/sync/range_collection.rs b/src/sync/range_collection.rs
index d212625be..822056ff4 100644
--- a/src/sync/range_collection.rs
+++ b/src/sync/range_collection.rs
@@ -29,7 +29,7 @@ pub trait RangeCollection<K, V> {
 	/// Remove all elements >= `tail`
 	fn insert_item(&mut self, key: K, value: V);
 	/// Get an iterator over ranges
-	fn range_iter<'c>(&'c self) -> RangeIterator<'c, K, V>;
+	fn range_iter(& self) -> RangeIterator<K, V>;
 }
 
 /// Range iterator. For each range yelds a key for the first element of the range and a vector of values.
@@ -60,7 +60,7 @@ impl<'c, K:'c, V:'c> Iterator for RangeIterator<'c, K, V> where K: Add<Output =
 }
 
 impl<K, V> RangeCollection<K, V> for Vec<(K, Vec<V>)> where K: Ord + PartialEq + Add<Output = K> + Sub<Output = K> + Copy + FromUsize + ToUsize {
-	fn range_iter<'c>(&'c self) -> RangeIterator<'c, K, V> {
+	fn range_iter(&self) -> RangeIterator<K, V> {
 		RangeIterator {
 			range: self.len(),
 			collection: self
diff --git a/src/views.rs b/src/views.rs
index 56e613f06..e1c704625 100644
--- a/src/views.rs
+++ b/src/views.rs
@@ -156,7 +156,7 @@ impl<'a> BlockView<'a> {
 
 	/// Return List of transactions in given block.
 	pub fn uncle_views(&self) -> Vec<HeaderView> {
-		self.rlp.at(2).iter().map(|rlp| HeaderView::new_from_rlp(rlp)).collect()
+		self.rlp.at(2).iter().map(HeaderView::new_from_rlp).collect()
 	}
 
 	/// Return list of uncle hashes of given block.