diff --git a/tests/mocking/mock_genesis.nim b/tests/mocking/mock_genesis.nim
index de2092da7..05f88a7db 100644
--- a/tests/mocking/mock_genesis.nim
+++ b/tests/mocking/mock_genesis.nim
@@ -10,22 +10,33 @@
 
 import
   # Specs
-  ../../beacon_chain/spec/datatypes/phase0,
-  ../../beacon_chain/spec/[beaconstate],
+  ../../beacon_chain/spec/[beaconstate, forks, state_transition],
   # Internals
   ../../beacon_chain/interop,
   # Mocking procs
   ./mock_deposits
 
-proc initGenesisState*(num_validators: uint64): phase0.HashedBeaconState =
+proc initGenesisState*(
+    num_validators: uint64 = 8'u64 * SLOTS_PER_EPOCH,
+    beaconStateFork: BeaconStateFork = forkPhase0): ref ForkedHashedBeaconState =
   let deposits = mockGenesisBalancedDeposits(
       validatorCount = num_validators,
       amountInEth = 32, # We create canonical validators with 32 Eth
       flags = {}
     )
 
-  initialize_hashed_beacon_state_from_eth1(
-    defaultRuntimeConfig, eth1BlockHash, 0, deposits, {})
+  var cfg = defaultRuntimeConfig
+  if beaconStateFork >= forkAltair:
+    cfg.ALTAIR_FORK_EPOCH = GENESIS_EPOCH
+
+  result = (ref ForkedHashedBeaconState)(
+    beaconStateFork: forkPhase0,
+    hbsPhase0: initialize_hashed_beacon_state_from_eth1(
+      cfg, eth1BlockHash, 0, deposits, {}))
+
+  maybeUpgradeStateToAltair(cfg, result[])
+
+  doAssert result.beaconStateFork == beaconStateFork
 
 when isMainModule:
   # Smoke test
diff --git a/tests/spec_block_processing/test_process_attestation.nim b/tests/spec_block_processing/test_process_attestation.nim
index a99f2b79f..287da629e 100644
--- a/tests/spec_block_processing/test_process_attestation.nim
+++ b/tests/spec_block_processing/test_process_attestation.nim
@@ -23,8 +23,7 @@ import
 suite "[Unit - Spec - Block processing] Attestations " & preset():
 
   const NumValidators = uint64(8) * SLOTS_PER_EPOCH
-  let genesisState = (ref ForkedHashedBeaconState)(
-    hbsPhase0: initGenesisState(NumValidators), beaconStateFork: forkPhase0)
+  let genesisState = initGenesisState(NumValidators)
 
   doAssert getStateField(genesisState[], validators).lenu64 == NumValidators
 
diff --git a/tests/spec_block_processing/test_process_deposits.nim b/tests/spec_block_processing/test_process_deposits.nim
index ccc34057d..f5dd9d415 100644
--- a/tests/spec_block_processing/test_process_deposits.nim
+++ b/tests/spec_block_processing/test_process_deposits.nim
@@ -16,7 +16,7 @@ import
   # Standard library
   std/math,
   # Specs
-  ../../beacon_chain/spec/[state_transition_block],
+  ../../beacon_chain/spec/[forks, state_transition_block],
   ../../beacon_chain/spec/datatypes/base,
   # Internals
   # Mock helpers
@@ -26,7 +26,7 @@ import
 suite "[Unit - Spec - Block processing] Deposits " & preset():
 
   const NumValidators = uint64 5 * SLOTS_PER_EPOCH
-  let genesisState = newClone(initGenesisState(NumValidators))
+  let genesisState = newClone(initGenesisState(NumValidators).hbsPhase0)
   doAssert genesisState.data.validators.lenu64 == NumValidators
 
   template valid_deposit(deposit_amount: uint64, name: string): untyped =
diff --git a/tests/spec_epoch_processing/test_process_justification_and_finalization.nim b/tests/spec_epoch_processing/test_process_justification_and_finalization.nim
index a0eff2a2d..99a79c3af 100644
--- a/tests/spec_epoch_processing/test_process_justification_and_finalization.nim
+++ b/tests/spec_epoch_processing/test_process_justification_and_finalization.nim
@@ -218,8 +218,7 @@ proc payload =
     echo "   Finalization rules are detailed at https://github.com/protolambda/eth2-docs#justification-and-finalization"
 
     const NumValidators = uint64(8) * SLOTS_PER_EPOCH
-    let genesisState = (ref ForkedHashedBeaconState)(
-      hbsPhase0: initGenesisState(NumValidators), beaconStateFork: forkPhase0)
+    let genesisState = initGenesisState(NumValidators)
     doAssert getStateField(genesisState[], validators).lenu64 == NumValidators
 
     setup: