diff --git a/ethcore/src/ethereum/mod.rs b/ethcore/src/ethereum/mod.rs
index 645644075..db07cbbd4 100644
--- a/ethcore/src/ethereum/mod.rs
+++ b/ethcore/src/ethereum/mod.rs
@@ -101,6 +101,9 @@ pub fn new_morden<'a, T: Into<SpecParams<'a>>>(params: T) -> Spec {
 /// Create a new Foundation Frontier-era chain spec as though it never changes to Homestead.
 pub fn new_frontier_test() -> Spec { load(None, include_bytes!("../../res/ethereum/frontier_test.json")) }
 
+/// Create a new Ropsten chain spec.
+pub fn new_ropsten_test() -> Spec { load(None, include_bytes!("../../res/ethereum/ropsten.json")) }
+
 /// Create a new Foundation Homestead-era chain spec as though it never changed from Frontier.
 pub fn new_homestead_test() -> Spec { load(None, include_bytes!("../../res/ethereum/homestead_test.json")) }
 
diff --git a/ethcore/src/machine.rs b/ethcore/src/machine.rs
index d54dd2e29..dbf66aa12 100644
--- a/ethcore/src/machine.rs
+++ b/ethcore/src/machine.rs
@@ -485,6 +485,25 @@ mod tests {
 		}
 	}
 
+	#[test]
+	fn should_disallow_unsigned_transactions() {
+		let rlp = "ea80843b9aca0083015f90948921ebb5f79e9e3920abe571004d0b1d5119c154865af3107a400080038080".into();
+		let transaction: UnverifiedTransaction = ::rlp::decode(&::rustc_hex::FromHex::from_hex(rlp).unwrap()).unwrap();
+		let spec = ::ethereum::new_ropsten_test();
+		let ethparams = get_default_ethash_extensions();
+
+		let machine = EthereumMachine::with_ethash_extensions(
+			spec.params().clone(),
+			Default::default(),
+			ethparams,
+		);
+		let mut header = ::header::Header::new();
+		header.set_number(15);
+
+		let res = machine.verify_transaction_basic(&transaction, &header);
+		assert_eq!(res, Err(transaction::Error::InvalidSignature("Crypto error (Invalid EC signature)".into())));
+	}
+
 	#[test]
 	fn ethash_gas_limit_is_multiple_of_determinant() {
 		use ethereum_types::U256;
diff --git a/ethcore/src/verification/verification.rs b/ethcore/src/verification/verification.rs
index 3b9104f0e..1275b5c5c 100644
--- a/ethcore/src/verification/verification.rs
+++ b/ethcore/src/verification/verification.rs
@@ -576,7 +576,17 @@ mod tests {
 			nonce: U256::from(2)
 		}.sign(keypair.secret(), None);
 
+		let tr3 = Transaction {
+			action: Action::Call(0x0.into()),
+			value: U256::from(0),
+			data: Bytes::new(),
+			gas: U256::from(30_000),
+			gas_price: U256::from(0),
+			nonce: U256::zero(),
+		}.null_sign(0);
+
 		let good_transactions = [ tr1.clone(), tr2.clone() ];
+		let eip86_transactions = [ tr3.clone() ];
 
 		let diff_inc = U256::from(0x40);
 
@@ -612,6 +622,7 @@ mod tests {
 		uncles_rlp.append_list(&good_uncles);
 		let good_uncles_hash = keccak(uncles_rlp.as_raw());
 		let good_transactions_root = ordered_trie_root(good_transactions.iter().map(|t| ::rlp::encode::<UnverifiedTransaction>(t)));
+		let eip86_transactions_root = ordered_trie_root(eip86_transactions.iter().map(|t| ::rlp::encode::<UnverifiedTransaction>(t)));
 
 		let mut parent = good.clone();
 		parent.set_number(9);
@@ -632,6 +643,14 @@ mod tests {
 
 		check_ok(basic_test(&create_test_block(&good), engine));
 
+		let mut bad_header = good.clone();
+		bad_header.set_transactions_root(eip86_transactions_root.clone());
+		bad_header.set_uncles_hash(good_uncles_hash.clone());
+		match basic_test(&create_test_block_with_data(&bad_header, &eip86_transactions, &good_uncles), engine) {
+			Err(Error(ErrorKind::Transaction(ref e), _)) if e == &::ethkey::Error::InvalidSignature.into() => (),
+			e => panic!("Block verification failed.\nExpected: Transaction Error (Invalid Signature)\nGot: {:?}", e),
+		}
+
 		let mut header = good.clone();
 		header.set_transactions_root(good_transactions_root.clone());
 		header.set_uncles_hash(good_uncles_hash.clone());
diff --git a/ethcore/transaction/src/transaction.rs b/ethcore/transaction/src/transaction.rs
index dd1e8ca2c..27b8b346c 100644
--- a/ethcore/transaction/src/transaction.rs
+++ b/ethcore/transaction/src/transaction.rs
@@ -409,6 +409,10 @@ impl UnverifiedTransaction {
 		if check_low_s && !(allow_empty_signature && self.is_unsigned()) {
 			self.check_low_s()?;
 		}
+		// Disallow unsigned transactions in case EIP-86 is disabled.
+		if !allow_empty_signature && self.is_unsigned() {
+			return Err(ethkey::Error::InvalidSignature.into());
+		}
 		// EIP-86: Transactions of this form MUST have gasprice = 0, nonce = 0, value = 0, and do NOT increment the nonce of account 0.
 		if allow_empty_signature && self.is_unsigned() && !(self.gas_price.is_zero() && self.value.is_zero() && self.nonce.is_zero()) {
 			return Err(ethkey::Error::InvalidSignature.into())