diff --git a/scripts/build_spec.py b/scripts/build_spec.py
index a16fa79ac..d7b6d0f59 100644
--- a/scripts/build_spec.py
+++ b/scripts/build_spec.py
@@ -16,6 +16,7 @@ PHASE0_IMPORTS = '''from typing import (
     Callable,
     Dict,
     List,
+    Optional,
     Set,
     Tuple,
 )
diff --git a/specs/core/0_beacon-chain.md b/specs/core/0_beacon-chain.md
index 1dcdbdef9..28d0d72cd 100644
--- a/specs/core/0_beacon-chain.md
+++ b/specs/core/0_beacon-chain.md
@@ -1176,8 +1176,12 @@ def get_genesis_beacon_state(deposits: List[Deposit], genesis_time: int, genesis
     )
 
     # Process genesis deposits
-    for deposit in deposits:
-        process_deposit(state, deposit)
+    for deposit_index, deposit in enumerate(deposits):
+        process_deposit(
+            state,
+            deposit,
+            deposit_index=deposit_index,
+        )
 
     # Process genesis activations
     for validator in state.validators:
@@ -1726,16 +1730,18 @@ def process_attestation(state: BeaconState, attestation: Attestation) -> None:
 ##### Deposits
 
 ```python
-def process_deposit(state: BeaconState, deposit: Deposit) -> None:
+def process_deposit(state: BeaconState, deposit: Deposit, deposit_index: Optional[uint64]) -> None:
     """
     Process an Eth1 deposit, registering a validator or increasing its balance.
     """
+    if deposit_index is None:
+        deposit_index = state.eth1_deposit_index
     # Verify the Merkle branch
     assert verify_merkle_branch(
         leaf=hash_tree_root(deposit.data),
         proof=deposit.proof,
         depth=DEPOSIT_CONTRACT_TREE_DEPTH,
-        index=state.eth1_deposit_index,
+        index=deposit_index,
         root=state.eth1_data.deposit_root,
     )
 
diff --git a/test_libs/pyspec/eth2spec/test/helpers/deposits.py b/test_libs/pyspec/eth2spec/test/helpers/deposits.py
index 20ff7440f..ca8b23361 100644
--- a/test_libs/pyspec/eth2spec/test/helpers/deposits.py
+++ b/test_libs/pyspec/eth2spec/test/helpers/deposits.py
@@ -4,25 +4,31 @@ from eth2spec.utils.merkle_minimal import calc_merkle_tree_from_leaves, get_merk
 from eth2spec.utils.ssz.ssz_impl import signing_root
 
 
-def build_deposit_data(spec, state, pubkey, privkey, amount, withdrawal_credentials, signed=False):
+def build_deposit_data(spec, pubkey, privkey, amount, withdrawal_credentials, state=None, signed=False):
     deposit_data = spec.DepositData(
         pubkey=pubkey,
         withdrawal_credentials=withdrawal_credentials,
         amount=amount,
     )
     if signed:
-        sign_deposit_data(spec, state, deposit_data, privkey)
+        sign_deposit_data(spec, deposit_data, privkey, state)
     return deposit_data
 
 
-def sign_deposit_data(spec, state, deposit_data, privkey):
-    signature = bls_sign(
-        message_hash=signing_root(deposit_data),
-        privkey=privkey,
-        domain=spec.get_domain(
+def sign_deposit_data(spec, deposit_data, privkey, state=None):
+    if state is None:
+        # Genesis
+        domain = spec.bls_domain(spec.DOMAIN_DEPOSIT)
+    else:
+        domain = spec.get_domain(
             state,
             spec.DOMAIN_DEPOSIT,
         )
+
+    signature = bls_sign(
+        message_hash=signing_root(deposit_data),
+        privkey=privkey,
+        domain=domain,
     )
     deposit_data.signature = signature
 
@@ -35,7 +41,7 @@ def build_deposit(spec,
                   amount,
                   withdrawal_credentials,
                   signed):
-    deposit_data = build_deposit_data(spec, state, pubkey, privkey, amount, withdrawal_credentials, signed)
+    deposit_data = build_deposit_data(spec, pubkey, privkey, amount, withdrawal_credentials, state=state, signed=signed)
 
     item = deposit_data.hash_tree_root()
     index = len(deposit_data_leaves)
@@ -54,6 +60,36 @@ def build_deposit(spec,
     return deposit, root, deposit_data_leaves
 
 
+def prepare_genesis_deposits(spec, genesis_validator_count, signed=False):
+    genesis_deposit_data_list = []
+    deposit_data_leaves = []
+    for validator_index in range(genesis_validator_count):
+        pubkey = pubkeys[validator_index]
+        privkey = privkeys[validator_index]
+        # insecurely use pubkey as withdrawal key if no credentials provided
+        withdrawal_credentials = spec.int_to_bytes(spec.BLS_WITHDRAWAL_PREFIX, length=1) + spec.hash(pubkey)[1:]
+        deposit_data = spec.DepositData(
+            pubkey=pubkey,
+            withdrawal_credentials=withdrawal_credentials,
+            amount=spec.MAX_EFFECTIVE_BALANCE,
+        )
+        if signed:
+            sign_deposit_data(spec, deposit_data, privkey)  # state=None
+        item = deposit_data.hash_tree_root()
+        deposit_data_leaves.append(item)
+        genesis_deposit_data_list.append(deposit_data)
+
+    tree = calc_merkle_tree_from_leaves(tuple(deposit_data_leaves))
+    root = get_merkle_root((tuple(deposit_data_leaves)))
+
+    genesis_deposits = (
+        spec.Deposit(proof=list(get_merkle_proof(tree, item_index=index)), data=deposit_data)
+        for index, deposit_data in enumerate(genesis_deposit_data_list) 
+    )
+
+    return genesis_deposits, root
+
+
 def prepare_state_and_deposit(spec, state, validator_index, amount, withdrawal_credentials=None, signed=False):
     """
     Prepare the state for the deposit, and create a deposit for the given validator, depositing the given amount.
diff --git a/test_libs/pyspec/eth2spec/test/sanity/test_genesis.py b/test_libs/pyspec/eth2spec/test/sanity/test_genesis.py
new file mode 100644
index 000000000..088df84e8
--- /dev/null
+++ b/test_libs/pyspec/eth2spec/test/sanity/test_genesis.py
@@ -0,0 +1,29 @@
+from eth2spec.test.context import spec_state_test, with_phases
+from eth2spec.test.helpers.deposits import (
+    prepare_genesis_deposits,
+)
+
+
+@with_phases(['phase0'])
+@spec_state_test
+def test_genesis(spec, state):
+    deposit_count = 2
+    genesis_deposits, deposit_root = prepare_genesis_deposits(spec, deposit_count)
+    genesis_time = 1234
+
+    yield genesis_deposits
+    yield genesis_time
+
+    genesis_eth1_data = spec.Eth1Data(
+        deposit_root=deposit_root,
+        deposit_count=deposit_count,
+        block_hash=b'\x12' * 32,
+    )
+
+    yield genesis_eth1_data
+    genesis_state = spec.get_genesis_beacon_state(
+        genesis_deposits,
+        genesis_time,
+        genesis_eth1_data,
+    )
+    yield genesis_state