diff --git a/rpc/src/v1/impls/eth.rs b/rpc/src/v1/impls/eth.rs
index 32e9b44b1..520b37045 100644
--- a/rpc/src/v1/impls/eth.rs
+++ b/rpc/src/v1/impls/eth.rs
@@ -340,7 +340,7 @@ impl<C, S, A, M, EM> Eth for EthClient<C, S, A, M, EM>
 						let seed_hash = Ethash::get_seedhash(b.block().header().number());
 						to_value(&(pow_hash, seed_hash, target))
 					}
-					_ => Err(Error::invalid_params())
+					_ => Err(Error::internal_error())
 				}
 			},
 			_ => Err(Error::invalid_params())
diff --git a/rpc/src/v1/tests/eth.rs b/rpc/src/v1/tests/eth.rs
index 6bc929709..280557e4b 100644
--- a/rpc/src/v1/tests/eth.rs
+++ b/rpc/src/v1/tests/eth.rs
@@ -43,12 +43,12 @@ fn sync_provider() -> Arc<TestSyncProvider> {
 }
 
 fn miner_service() -> Arc<TestMinerService> {
-	Arc::new(TestMinerService)
+	Arc::new(TestMinerService::default())
 }
 
 struct EthTester {
-	client: Arc<TestBlockChainClient>,
-	_sync: Arc<TestSyncProvider>,
+	pub client: Arc<TestBlockChainClient>,
+	pub sync: Arc<TestSyncProvider>,
 	_accounts_provider: Arc<TestAccountProvider>,
 	_miner: Arc<TestMinerService>,
 	hashrates: Arc<RwLock<HashMap<H256, U256>>>,
@@ -68,7 +68,7 @@ impl Default for EthTester {
 		io.add_delegate(eth);
 		EthTester {
 			client: client,
-			_sync: sync,
+			sync: sync,
 			_accounts_provider: ap,
 			_miner: miner,
 			io: io,
@@ -346,5 +346,25 @@ fn rpc_eth_compile_serpent() {
 	assert_eq!(EthTester::default().io.handle_request(request), Some(response.to_owned()));
 }
 
+#[test]
+fn returns_no_work_if_cant_mine() {
+	let eth_tester = EthTester::default();
 
+	let request = r#"{"jsonrpc": "2.0", "method": "eth_getWork", "params": [], "id": 1}"#;
+	let response = r#"{"jsonrpc":"2.0","result":["","",""],"id":1}"#;
 
+	assert_eq!(eth_tester.io.handle_request(request), Some(response.to_owned()));
+}
+
+#[test]
+fn returns_error_if_can_mine_and_no_closed_block() {
+	use ethsync::{SyncState};
+
+	let eth_tester = EthTester::default();
+	eth_tester.sync.status.write().unwrap().state = SyncState::Idle;
+
+	let request = r#"{"jsonrpc": "2.0", "method": "eth_getWork", "params": [], "id": 1}"#;
+	let response = r#"{"jsonrpc":"2.0","error":{"code":-32603,"message":"Internal error","data":null},"id":1}"#;
+
+	assert_eq!(eth_tester.io.handle_request(request), Some(response.to_owned()));
+}
diff --git a/rpc/src/v1/tests/helpers/miner_service.rs b/rpc/src/v1/tests/helpers/miner_service.rs
index 0cddf2a1e..3a60bd136 100644
--- a/rpc/src/v1/tests/helpers/miner_service.rs
+++ b/rpc/src/v1/tests/helpers/miner_service.rs
@@ -22,7 +22,19 @@ use ethcore::block::ClosedBlock;
 use ethcore::transaction::SignedTransaction;
 use ethminer::{MinerService, MinerStatus};
 
-pub struct TestMinerService;
+pub struct TestMinerService {
+	pub imported_transactions: RwLock<Vec<H256>>,
+	pub latest_closed_block: Mutex<Option<ClosedBlock>>,
+}
+
+impl Default for TestMinerService {
+	fn default() -> TestMinerService {
+		TestMinerService {
+			imported_transactions: RwLock::new(Vec::new()),
+			latest_closed_block: Mutex::new(None),
+		}
+	}
+}
 
 impl MinerService for TestMinerService {
 
@@ -45,9 +57,11 @@ impl MinerService for TestMinerService {
 	fn prepare_sealing(&self, _chain: &BlockChainClient) { unimplemented!(); }
 
 	/// Grab the `ClosedBlock` that we want to be sealed. Comes as a mutex that you have to lock.
-	fn sealing_block(&self, _chain: &BlockChainClient) -> &Mutex<Option<ClosedBlock>> { unimplemented!(); }
+	fn sealing_block(&self, _chain: &BlockChainClient) -> &Mutex<Option<ClosedBlock>> {
+		&self.latest_closed_block
+	}
 
 	/// Submit `seal` as a valid solution for the header of `pow_hash`.
 	/// Will check the seal, but not actually insert the block into the chain.
 	fn submit_seal(&self, _chain: &BlockChainClient, _pow_hash: H256, _seal: Vec<Bytes>) -> Result<(), Error> { unimplemented!(); }
-}
\ No newline at end of file
+}
diff --git a/rpc/src/v1/tests/helpers/sync_provider.rs b/rpc/src/v1/tests/helpers/sync_provider.rs
index 631752dfc..bfbfad44b 100644
--- a/rpc/src/v1/tests/helpers/sync_provider.rs
+++ b/rpc/src/v1/tests/helpers/sync_provider.rs
@@ -15,6 +15,7 @@
 // along with Parity.  If not, see <http://www.gnu.org/licenses/>.
 
 use ethsync::{SyncProvider, SyncStatus, SyncState};
+use std::sync::{RwLock};
 
 pub struct Config {
 	pub protocol_version: u8,
@@ -22,13 +23,13 @@ pub struct Config {
 }
 
 pub struct TestSyncProvider {
-	status: SyncStatus,
+	pub status: RwLock<SyncStatus>,
 }
 
 impl TestSyncProvider {
 	pub fn new(config: Config) -> Self {
 		TestSyncProvider {
-			status: SyncStatus {
+			status: RwLock::new(SyncStatus {
 				state: SyncState::NotSynced,
 				protocol_version: config.protocol_version,
 				start_block_number: 0,
@@ -39,14 +40,14 @@ impl TestSyncProvider {
 				num_peers: config.num_peers,
 				num_active_peers: 0,
 				mem_used: 0,
-			},
+			})
 		}
 	}
 }
 
 impl SyncProvider for TestSyncProvider {
 	fn status(&self) -> SyncStatus {
-		self.status.clone()
+		self.status.read().unwrap().clone()
 	}
 }