diff --git a/ethcore/src/engines/authority_round/mod.rs b/ethcore/src/engines/authority_round/mod.rs
index c0d607e98c5..975246c6c1f 100644
--- a/ethcore/src/engines/authority_round/mod.rs
+++ b/ethcore/src/engines/authority_round/mod.rs
@@ -456,7 +456,6 @@ impl Engine<EthereumMachine> for AuthorityRound {
 	}
 
 	fn populate_from_parent(&self, header: &mut Header, parent: &Header) {
-		// Chain scoring: total weight is sqrt(U256::max_value())*height - step
 		let new_difficulty = U256::from(U128::max_value()) + header_step(parent).expect("Header has been verified; qed").into() - self.step.load().into();
 		header.set_difficulty(new_difficulty);
 	}