diff --git a/ethcore/src/block_queue.rs b/ethcore/src/block_queue.rs
index 1fe31ba19..009ab6bf7 100644
--- a/ethcore/src/block_queue.rs
+++ b/ethcore/src/block_queue.rs
@@ -79,6 +79,8 @@ struct Verification {
 	bad: HashSet<H256>,
 }
 
+const MAX_UNVERIFIED_QUEUE_SIZE: usize = 50000;
+
 impl BlockQueue {
 	/// Creates a new queue instance.
 	pub fn new(engine: Arc<Box<Engine>>, message_channel: IoChannel<NetSyncMessage>) -> BlockQueue {
@@ -290,7 +292,7 @@ impl BlockQueue {
 	pub fn queue_info(&self) -> BlockQueueInfo {
 		let verification = self.verification.lock().unwrap();
 		BlockQueueInfo {
-			full: false,
+			full: verification.unverified.len() + verification.verifying.len() >= MAX_UNVERIFIED_QUEUE_SIZE,
 			verified_queue_size: verification.verified.len(),
 			unverified_queue_size: verification.unverified.len(),
 			verifying_queue_size: verification.verifying.len(),
diff --git a/sync/src/chain.rs b/sync/src/chain.rs
index 9752a5013..9ae00670f 100644
--- a/sync/src/chain.rs
+++ b/sync/src/chain.rs
@@ -292,7 +292,7 @@ impl ChainSync {
 			trace!(target: "sync", "Ignored unexpected block headers");
 			return Ok(());
 		}
-		if self.state == SyncState::Waiting {
+		if io.chain().queue_info().full {
 			trace!(target: "sync", "Ignored block headers while waiting");
 			return Ok(());
 		}
@@ -376,7 +376,7 @@ impl ChainSync {
 			trace!(target: "sync", "Ignored unexpected block bodies");
 			return Ok(());
 		}
-		if self.state  == SyncState::Waiting {
+		if io.chain().queue_info().full {
 			trace!(target: "sync", "Ignored block bodies while waiting");
 			return Ok(());
 		}
@@ -532,7 +532,7 @@ impl ChainSync {
 	/// Enter waiting state
 	fn pause_sync(&mut self) {
 		trace!(target: "sync", "Block queue full, pausing sync");
-		self.state = SyncState::Waiting;
+		//self.state = SyncState::Waiting;
 	}
 
 	/// Find something to do for a peer. Called for a new peer or when a peer is done with it's task.