diff --git a/specs/core/0_beacon-chain.md b/specs/core/0_beacon-chain.md
index 20d7f5d43..615c66048 100644
--- a/specs/core/0_beacon-chain.md
+++ b/specs/core/0_beacon-chain.md
@@ -1345,7 +1345,7 @@ For convenience, we provide the interface to the contract here:
 
 * `__init__()`: initializes the contract
 * `get_deposit_root() -> bytes32`: returns the current root of the deposit tree
-* `deposit(bytes[512])`: adds a deposit instance to the deposit tree, incorporating the input argument and the value transferred in the given call. Note: the amount of value transferred *must* be within `MIN_DEPOSIT_AMOUNT` and `MAX_DEPOSIT_AMOUNT`, inclusive. Each of these constants are specified in units of Gwei.
+* `def deposit(pubkey: bytes[48], withdrawal_credentials: bytes[32], signature: bytes[96])`: adds a deposit instance to the deposit tree, incorporating the input arguments and the value transferred in the given call. Note: the amount of value transferred *must* be within `MIN_DEPOSIT_AMOUNT` and `MAX_DEPOSIT_AMOUNT`, inclusive. Each of these constants are specified in units of Gwei.
 
 ## On genesis
 
diff --git a/specs/validator/0_beacon-chain-validator.md b/specs/validator/0_beacon-chain-validator.md
index 632bf2b62..966e238ab 100644
--- a/specs/validator/0_beacon-chain-validator.md
+++ b/specs/validator/0_beacon-chain-validator.md
@@ -101,11 +101,10 @@ In phase 0, all incoming validator deposits originate from the Ethereum 1.0 PoW
 To submit a deposit:
 
 * Pack the validator's [initialization parameters](#initialization) into `deposit_data`, a [`DepositData`](../core/0_beacon-chain.md#depositdata) SSZ object.
-* Let `proof_of_possession` be the result of `bls_sign` of the `signing_root(deposit_data)` with `domain=DOMAIN_DEPOSIT`.
-* Set `deposit_data.proof_of_possession = proof_of_possession`.
 * Let `amount` be the amount in Gwei to be deposited by the validator where `MIN_DEPOSIT_AMOUNT <= amount <= MAX_DEPOSIT_AMOUNT`.
 * Set `deposit_data.amount = amount`.
-* Send a transaction on the Ethereum 1.0 chain to `DEPOSIT_CONTRACT_ADDRESS` executing `deposit(deposit_input: bytes[512])` along with `serialize(deposit_data)` as the singular `bytes` input along with a deposit of `amount` Gwei.
+* Let `signature` be the result of `bls_sign` of the `signing_root(deposit_data)` with `domain=DOMAIN_DEPOSIT`.
+* Send a transaction on the Ethereum 1.0 chain to `DEPOSIT_CONTRACT_ADDRESS` executing `def deposit(pubkey: bytes[48], withdrawal_credentials: bytes[32], signature: bytes[96])` along with a deposit of `amount` Gwei.
 
 _Note_: Deposits made for the same `pubkey` are treated as for the same validator. A singular `Validator` will be added to `state.validator_registry` with each additional deposit amount added to the validator's balance. A validator can only be activated when total deposits for the validator pubkey meet or exceed `MAX_DEPOSIT_AMOUNT`.