diff --git a/specs/core/0_beacon-chain.md b/specs/core/0_beacon-chain.md
index 1efd98d4b..1600519f5 100644
--- a/specs/core/0_beacon-chain.md
+++ b/specs/core/0_beacon-chain.md
@@ -803,6 +803,7 @@ For each `AttestationRecord` object:
 * Derive a group public key by adding the public keys of all of the attesters in `attestation_indices` for whom the corresponding bit in `attester_bitfield` (the ith bit is `(attester_bitfield[i // 8] >> (7 - (i %8))) % 2`) equals 1.
 * Let `fork_version = pre_fork_version if slot < fork_slot_number else post_fork_version`.
 * Verify that `aggregate_sig` verifies using the group pubkey generated and the serialized form of `AttestationSignedData(fork_version, slot, shard, parent_hashes, shard_block_hash, last_crosslinked_hash, shard_block_combined_data_root, justified_slot)` as the message.
+* [TO BE REMOVED IN PHASE 1] Verify that `shard_block_hash == bytes([0] * 32)`
 
 Extend the list of `AttestationRecord` objects in the `state` with those included in the block, ordering the new additions in the same order as they came in the block.