diff --git a/ethcore/src/engines/authority_round.rs b/ethcore/src/engines/authority_round.rs
index c278a011a..f28a06117 100644
--- a/ethcore/src/engines/authority_round.rs
+++ b/ethcore/src/engines/authority_round.rs
@@ -274,7 +274,6 @@ impl Engine for AuthorityRound {
 	}
 
 	fn verify_block_family(&self, header: &Header, parent: &Header, _block: Option<&[u8]>) -> Result<(), Error> {
-		// Don't calculate difficulty for genesis blocks.
 		if header.number() == 0 {
 			return Err(From::from(BlockError::RidiculousNumber(OutOfBounds { min: Some(1), max: None, found: header.number() })));
 		}
@@ -286,10 +285,6 @@ impl Engine for AuthorityRound {
 			try!(Err(BlockError::DoubleVote(header.author().clone())));
 		}
 
-		// Check difficulty is correct given the two timestamps.
-		if header.difficulty() != parent.difficulty() {
-			return Err(From::from(BlockError::InvalidDifficulty(Mismatch { expected: *parent.difficulty(), found: *header.difficulty() })))
-		}
 		let gas_limit_divisor = self.our_params.gas_limit_bound_divisor;
 		let min_gas = parent.gas_limit().clone() - parent.gas_limit().clone() / gas_limit_divisor;
 		let max_gas = parent.gas_limit().clone() + parent.gas_limit().clone() / gas_limit_divisor;
diff --git a/ethcore/src/ethereum/ethash.rs b/ethcore/src/ethereum/ethash.rs
index 0ca9ff00e..96c1298cc 100644
--- a/ethcore/src/ethereum/ethash.rs
+++ b/ethcore/src/ethereum/ethash.rs
@@ -328,12 +328,12 @@ impl Engine for Ethash {
 		t.sender().map(|_|()) // Perform EC recovery and cache sender
 	}
 
-	/// Check if a new block should replace the best blockchain block.
 	fn is_new_best_block(&self, best_total_difficulty: U256, _best_header: HeaderView, parent_details: &BlockDetails, new_header: &HeaderView) -> bool {
 		is_new_best_block(best_total_difficulty, parent_details, new_header)
 	}
 }
 
+/// Check if a new block should replace the best blockchain block.
 pub fn is_new_best_block(best_total_difficulty: U256, parent_details: &BlockDetails, new_header: &HeaderView) -> bool {
 	parent_details.total_difficulty + new_header.difficulty() > best_total_difficulty
 }