diff --git a/verification/src/timestamp.rs b/verification/src/timestamp.rs
index 3aef250e..5c1487ad 100644
--- a/verification/src/timestamp.rs
+++ b/verification/src/timestamp.rs
@@ -1,4 +1,3 @@
-use std::collections::BTreeSet;
 use chain::BlockHeader;
 use db::{BlockHeaderProvider, BlockAncestors};
 use primitives::hash::H256;
@@ -14,7 +13,7 @@ pub fn median_timestamp(header: &BlockHeader, store: &BlockHeaderProvider) -> u3
 /// The header should be later expected to have higher timestamp
 /// than this median timestamp
 pub fn median_timestamp_inclusive(previous_header_hash: H256, store: &BlockHeaderProvider) -> u32 {
-	let timestamps: BTreeSet<_> = BlockAncestors::new(previous_header_hash.clone().into(), store)
+	let mut timestamps: Vec<_> = BlockAncestors::new(previous_header_hash.clone().into(), store)
 		.take(11)
 		.map(|header| header.time)
 		.collect();
@@ -23,6 +22,6 @@ pub fn median_timestamp_inclusive(previous_header_hash: H256, store: &BlockHeade
 		return 0;
 	}
 
-	let timestamps = timestamps.into_iter().collect::<Vec<_>>();
+	timestamps.sort();
 	timestamps[timestamps.len() / 2]
 }