diff --git a/sync/src/block_sync.rs b/sync/src/block_sync.rs
index ff5411140..eea977906 100644
--- a/sync/src/block_sync.rs
+++ b/sync/src/block_sync.rs
@@ -258,6 +258,12 @@ impl BlockDownloader {
 					self.blocks.reset_to(hashes);
 					self.state = State::Blocks;
 					return Ok(DownloadAction::Reset);
+				} else {
+					let best = io.chain().chain_info().best_block_number;
+					if best > self.last_imported_block && best - self.last_imported_block > MAX_REORG_BLOCKS {
+						trace!(target: "sync", "No common block, disabling peer");
+						return Err(BlockDownloaderImportError::Invalid);
+					}
 				}
 			},
 			State::Blocks => {
diff --git a/sync/src/tests/chain.rs b/sync/src/tests/chain.rs
index 5fe34428e..7705215f5 100644
--- a/sync/src/tests/chain.rs
+++ b/sync/src/tests/chain.rs
@@ -250,3 +250,14 @@ fn high_td_attach() {
 	assert_eq!(net.peer(0).chain.chain_info().best_block_number, 5);
 }
 
+
+#[test]
+fn disconnect_on_unrelated_chain() {
+	::env_logger::init().ok();
+	let mut net = TestNet::new(2);
+	net.peer_mut(0).chain.add_blocks(200, EachBlockWith::Uncle);
+	net.peer_mut(1).chain.add_blocks(100, EachBlockWith::Nothing);
+	net.sync();
+	assert_eq!(net.disconnect_events, vec![(0, 0)]);
+}
+
diff --git a/sync/src/tests/helpers.rs b/sync/src/tests/helpers.rs
index d5e07a936..b1c04f84e 100644
--- a/sync/src/tests/helpers.rs
+++ b/sync/src/tests/helpers.rs
@@ -123,6 +123,7 @@ pub struct TestPeer {
 pub struct TestNet {
 	pub peers: Vec<TestPeer>,
 	pub started: bool,
+	pub disconnect_events: Vec<(PeerId, PeerId)>, //disconnected (initiated by, to)
 }
 
 impl TestNet {
@@ -140,6 +141,7 @@ impl TestNet {
 		let mut net = TestNet {
 			peers: Vec::new(),
 			started: false,
+			disconnect_events: Vec::new(),
 		};
 		for _ in 0..n {
 			let chain = TestBlockChainClient::new();
@@ -190,6 +192,7 @@ impl TestNet {
 						// notify this that disconnecting peers are disconnecting
 						let mut io = TestIo::new(&mut p.chain, &p.snapshot_service, &mut p.queue, Some(*d));
 						p.sync.write().on_peer_aborting(&mut io, *d);
+						self.disconnect_events.push((peer, *d));
 					}
 					to_disconnect
 				};