diff --git a/src/ethereum/ethash.rs b/src/ethereum/ethash.rs
index aebee1e92..057a67d20 100644
--- a/src/ethereum/ethash.rs
+++ b/src/ethereum/ethash.rs
@@ -99,6 +99,10 @@ impl Engine for Ethash {
 	}
 
 	fn verify_block_basic(&self, header: &Header, _block: Option<&[u8]>) -> result::Result<(), Error> {
+		// check the seal fields.
+		try!(UntrustedRlp::new(&header.seal[0]).as_val::<H256>());
+		try!(UntrustedRlp::new(&header.seal[1]).as_val::<u64>());
+
 		let min_difficulty = decode(self.spec().engine_params.get("minimumDifficulty").unwrap());
 		if header.difficulty < min_difficulty {
 			return Err(From::from(BlockError::InvalidDifficulty(Mismatch { expected: min_difficulty, found: header.difficulty })))
diff --git a/src/tests/chain.rs b/src/tests/chain.rs
index e7b1759f2..8be1b1c92 100644
--- a/src/tests/chain.rs
+++ b/src/tests/chain.rs
@@ -31,9 +31,22 @@ fn do_json_test(json_data: &[u8]) -> Vec<String> {
 			dir.push(H32::random().hex());
 			{
 				let client = Client::new(spec, &dir, IoChannel::disconnected()).unwrap();
-				blocks.into_iter().foreach(|b| {
+				for b in blocks.into_iter() {
+					{
+						let urlp = UntrustedRlp::new(&b);
+						if !urlp.is_list() || urlp.item_count() != 3 || urlp.size() != b.len() { continue; }
+						if urlp.val_at::<Header>(0).is_err() { continue; }
+						if !urlp.at(1).unwrap().is_list() { continue; }
+						if urlp.at(1).unwrap().iter().find(|i| i.as_val::<Transaction>().is_err()).is_some() {
+							continue;
+						}
+						if !urlp.at(2).unwrap().is_list() { continue; }
+						if urlp.at(2).unwrap().iter().find(|i| i.as_val::<Header>().is_err()).is_some() {
+							continue;
+						}
+					}
 					client.import_block(b).unwrap();
-				});
+				}
 				client.flush_queue();
 				client.import_verified_blocks(&IoChannel::disconnected());
 				fail_unless(client.chain_info().best_block_hash == H256::from_json(&test["lastblockhash"]));
@@ -50,16 +63,16 @@ fn do_json_test(json_data: &[u8]) -> Vec<String> {
 
 declare_test!{BlockchainTests_bcBlockGasLimitTest, "BlockchainTests/bcBlockGasLimitTest"}
 declare_test!{BlockchainTests_bcForkBlockTest, "BlockchainTests/bcForkBlockTest"}
-declare_test!{ignore => BlockchainTests_bcForkStressTest, "BlockchainTests/bcForkStressTest"}				// FAILS
-declare_test!{ignore => BlockchainTests_bcForkUncle, "BlockchainTests/bcForkUncle"}							// FAILS
+declare_test!{BlockchainTests_bcForkStressTest, "BlockchainTests/bcForkStressTest"}				// STILL FAILS
+declare_test!{BlockchainTests_bcForkUncle, "BlockchainTests/bcForkUncle"}						// STILL FAILS
 declare_test!{BlockchainTests_bcGasPricerTest, "BlockchainTests/bcGasPricerTest"}
 declare_test!{BlockchainTests_bcInvalidHeaderTest, "BlockchainTests/bcInvalidHeaderTest"}
-declare_test!{ignore => BlockchainTests_bcInvalidRLPTest, "BlockchainTests/bcInvalidRLPTest"}				// FAILS
-declare_test!{ignore => BlockchainTests_bcMultiChainTest, "BlockchainTests/bcMultiChainTest"}				// FAILS
+declare_test!{BlockchainTests_bcInvalidRLPTest, "BlockchainTests/bcInvalidRLPTest"}				// FAILS
+declare_test!{BlockchainTests_bcMultiChainTest, "BlockchainTests/bcMultiChainTest"}				// FAILS
 declare_test!{BlockchainTests_bcRPC_API_Test, "BlockchainTests/bcRPC_API_Test"}
 declare_test!{BlockchainTests_bcStateTest, "BlockchainTests/bcStateTest"}
 declare_test!{BlockchainTests_bcTotalDifficultyTest, "BlockchainTests/bcTotalDifficultyTest"}
-declare_test!{ignore => BlockchainTests_bcUncleHeaderValiditiy, "BlockchainTests/bcUncleHeaderValiditiy"}	// FAILS
-declare_test!{ignore => BlockchainTests_bcUncleTest, "BlockchainTests/bcUncleTest"}							// FAILS
-declare_test!{ignore => BlockchainTests_bcValidBlockTest, "BlockchainTests/bcValidBlockTest"}				// FAILS
-declare_test!{ignore => BlockchainTests_bcWalletTest, "BlockchainTests/bcWalletTest"}						// FAILS
+declare_test!{BlockchainTests_bcUncleHeaderValiditiy, "BlockchainTests/bcUncleHeaderValiditiy"}	// FAILS
+declare_test!{BlockchainTests_bcUncleTest, "BlockchainTests/bcUncleTest"}						// FAILS
+declare_test!{BlockchainTests_bcValidBlockTest, "BlockchainTests/bcValidBlockTest"}				// FAILS
+declare_test!{BlockchainTests_bcWalletTest, "BlockchainTests/bcWalletTest"}						// FAILS