diff --git a/src/bin/client.rs b/src/bin/client.rs
index f8b29ac1c..a644ecd1b 100644
--- a/src/bin/client.rs
+++ b/src/bin/client.rs
@@ -11,16 +11,15 @@ use util::network::{NetworkService};
 use ethcore::client::Client;
 use ethcore::sync::EthSync;
 use ethcore::ethereum;
-use ethcore::ethereum::ethash::Ethash;
 
 fn main() {
 	::env_logger::init().ok();
 	let mut service = NetworkService::start().unwrap();
 	//TODO: replace with proper genesis and chain params.
-	let engine = Ethash::new_arc(ethereum::new_frontier());
+	let spec = ethereum::new_frontier();
 	let mut dir = env::temp_dir();
 	dir.push(H32::random().hex());
-	let client = Arc::new(Client::new(engine, &dir));
+	let client = Arc::new(Client::new(spec, &dir).unwrap());
 	EthSync::register(&mut service, client);
 	loop {
 		let mut cmd = String::new();
diff --git a/src/client.rs b/src/client.rs
index 019bdf797..b914dba19 100644
--- a/src/client.rs
+++ b/src/client.rs
@@ -1,8 +1,9 @@
 use util::*;
 use blockchain::BlockChain;
 use views::BlockView;
-use error::ImportError;
+use error::*;
 use header::BlockNumber;
+use spec::Spec;
 use engine::Engine;
 
 /// General block status
@@ -95,16 +96,17 @@ pub trait BlockChainClient : Sync {
 /// Blockchain database client backed by a persistent database. Owns and manages a blockchain and a block queue.
 pub struct Client {
 	chain: Arc<BlockChain>,
-	_engine: Arc<Engine>,
+	_engine: Arc<Box<Engine>>,
 }
 
 impl Client {
-	pub fn new(engine: Arc<Engine>, path: &Path) -> Client {
-		let chain = Arc::new(BlockChain::new(&engine.spec().genesis_block(), path));
-		Client {
+	pub fn new(spec: Spec, path: &Path) -> Result<Client, Error> {
+		let chain = Arc::new(BlockChain::new(&spec.genesis_block(), path));
+		let engine = Arc::new(try!(spec.to_engine()));
+		Ok(Client {
 			chain: chain.clone(),
-			_engine: engine.clone(),
-		}
+			_engine: engine,
+		})
 	}
 }
 
diff --git a/src/ethereum/ethash.rs b/src/ethereum/ethash.rs
index d260e21b4..828441fd6 100644
--- a/src/ethereum/ethash.rs
+++ b/src/ethereum/ethash.rs
@@ -13,10 +13,6 @@ impl Ethash {
 	pub fn new_boxed(spec: Spec) -> Box<Engine> {
 		Box::new(Ethash{spec: spec})
 	}
-
-	pub fn new_arc(spec: Spec) -> Arc<Engine> {
-		Arc::new(Ethash{spec: spec})
-	}
 }
 
 impl Engine for Ethash {
diff --git a/src/sync/mod.rs b/src/sync/mod.rs
index aca40ffba..300465014 100644
--- a/src/sync/mod.rs
+++ b/src/sync/mod.rs
@@ -13,13 +13,11 @@
 /// use ethcore::client::Client;
 /// use ethcore::sync::EthSync;
 /// use ethcore::ethereum;
-/// use ethcore::ethereum::ethash::Ethash;
 ///
 /// fn main() {
 /// 	let mut service = NetworkService::start().unwrap();
-/// 	let engine = Ethash::new_arc(ethereum::new_frontier());
 /// 	let dir = env::temp_dir();
-/// 	let client = Arc::new(Client::new(engine, &dir));
+/// 	let client = Arc::new(Client::new(ethereum::new_frontier(), &dir).unwrap());
 /// 	EthSync::register(&mut service, client);
 /// }
 /// ```