diff --git a/ethcore/sync/src/chain/mod.rs b/ethcore/sync/src/chain/mod.rs
index 50f4c9428..ef5146f91 100644
--- a/ethcore/sync/src/chain/mod.rs
+++ b/ethcore/sync/src/chain/mod.rs
@@ -761,14 +761,24 @@ impl ChainSync {
 						}
 					}
 
-					// Only ask for old blocks if the peer has a higher difficulty
-					if force || higher_difficulty {
+					// Only ask for old blocks if the peer has a higher difficulty than the last imported old block
+					let last_imported_old_block_difficulty = self.old_blocks.as_mut().and_then(|d| {
+						io.chain().block_total_difficulty(BlockId::Number(d.last_imported_block_number()))
+					});
+
+					if force || last_imported_old_block_difficulty.map_or(true, |ld| peer_difficulty.map_or(true, |pd| pd > ld)) {
 						if let Some(request) = self.old_blocks.as_mut().and_then(|d| d.request_blocks(io, num_active_peers)) {
 							SyncRequester::request_blocks(self, io, peer_id, request, BlockSet::OldBlocks);
 							return;
 						}
 					} else {
-						trace!(target: "sync", "peer {} is not suitable for asking old blocks", peer_id);
+						trace!(
+							target: "sync",
+							"peer {:?} is not suitable for requesting old blocks, last_imported_old_block_difficulty={:?}, peer_difficulty={:?}",
+							peer_id,
+							last_imported_old_block_difficulty,
+							peer_difficulty
+						);
 						self.deactivate_peer(io, peer_id);
 					}
 				},