diff --git a/beacon_chain/rpc/rest_validator_api.nim b/beacon_chain/rpc/rest_validator_api.nim
index 5c45dbbf1..ce3e31f62 100644
--- a/beacon_chain/rpc/rest_validator_api.nim
+++ b/beacon_chain/rpc/rest_validator_api.nim
@@ -215,7 +215,7 @@ proc installValidatorApiHandlers*(router: var RestRouter, node: BeaconNode) =
             for idx, pubkey in syncCommittee:
               if pubkey == res[resIdx].pubkey:
                 res[resIdx].validator_sync_committee_indices.add(
-                  ValidatorIndexInSyncCommittee idx)
+                  IndexInSyncCommittee idx)
           res
 
       return RestApiResponse.jsonResponse(duties)
diff --git a/beacon_chain/spec/beaconstate.nim b/beacon_chain/spec/beaconstate.nim
index c1d84e664..afa6ac3ff 100644
--- a/beacon_chain/spec/beaconstate.nim
+++ b/beacon_chain/spec/beaconstate.nim
@@ -19,9 +19,6 @@ import
 
 export extras, forks, validator
 
-type
-  SomeBeaconState* = phase0.BeaconState | altair.BeaconState | merge.BeaconState
-
 # https://github.com/ethereum/consensus-specs/blob/v1.1.5/specs/phase0/beacon-chain.md#increase_balance
 func increase_balance*(balance: var Gwei, delta: Gwei) =
   balance += delta
@@ -864,6 +861,6 @@ func upgrade_to_merge*(cfg: RuntimeConfig, pre: altair.BeaconState):
     latest_execution_payload_header: ExecutionPayloadHeader()
   )
 
-template isValidInState*(idx: ValidatorIndex, state: SomeBeaconState): bool =
-  idx.int < state.validators.len
+template isValidInState*(idx: ValidatorIndex, state: ForkyBeaconState): bool =
+  idx.uint64 < state.validators.lenu64
 
diff --git a/beacon_chain/spec/datatypes/altair.nim b/beacon_chain/spec/datatypes/altair.nim
index f5e4b9a90..13d3c95d1 100644
--- a/beacon_chain/spec/datatypes/altair.nim
+++ b/beacon_chain/spec/datatypes/altair.nim
@@ -432,7 +432,7 @@ type
   SomeBeaconBlockBody* = BeaconBlockBody | SigVerifiedBeaconBlockBody | TrustedBeaconBlockBody
 
   SyncSubcommitteeIndex* = distinct uint8
-  ValidatorIndexInSyncCommittee* = distinct uint16
+  IndexInSyncCommittee* = distinct uint16
 
   BeaconStateDiff* = object
     # Small and/or static; always include
@@ -501,7 +501,7 @@ template `[]`*(a: auto; i: SyncSubcommitteeIndex): auto =
   a[i.asInt]
 
 template `[]`*(arr: array[SYNC_COMMITTEE_SIZE, any] | seq;
-               idx: ValidatorIndexInSyncCommittee): auto =
+               idx: IndexInSyncCommittee): auto =
   arr[int idx]
 
 template `==`*(x, y: SyncSubcommitteeIndex): bool =
diff --git a/beacon_chain/spec/eth2_apis/eth2_rest_serialization.nim b/beacon_chain/spec/eth2_apis/eth2_rest_serialization.nim
index 7bb6f18c6..3ca9edb2d 100644
--- a/beacon_chain/spec/eth2_apis/eth2_rest_serialization.nim
+++ b/beacon_chain/spec/eth2_apis/eth2_rest_serialization.nim
@@ -6,16 +6,16 @@
 
 import std/typetraits
 import stew/[assign2, results, base10, byteutils, endians2], presto/common,
-       libp2p/peerid, serialization,
-       json_serialization, json_serialization/std/[options, net, sets],
-       nimcrypto/utils as ncrutils
+       libp2p/peerid, nimcrypto/utils as ncrutils
 import "."/rest_types,
        ".."/[eth2_ssz_serialization, forks],
        ".."/datatypes/[phase0, altair, merge]
 
+import serialization, json_serialization, json_serialization/std/[options, net, sets]
+
 export
-  results, peerid, common, serialization, json_serialization, options, net, sets,
-  eth2_ssz_serialization, rest_types
+  eth2_ssz_serialization, results, peerid, common, serialization,
+  json_serialization, options, net, sets, rest_types
 
 from web3/ethtypes import BlockHash
 export ethtypes.BlockHash
@@ -430,21 +430,21 @@ proc readValue*(reader: var JsonReader[RestJson], value: var ValidatorIndex)
   else:
     reader.raiseUnexpectedValue($res.error())
 
-proc writeValue*(writer: var JsonWriter[RestJson], value: ValidatorIndexInSyncCommittee)
+proc writeValue*(writer: var JsonWriter[RestJson], value: IndexInSyncCommittee)
                 {.raises: [IOError, Defect].} =
   writeValue(writer, Base10.toString(distinctBase(value)))
 
-proc readValue*(reader: var JsonReader[RestJson], value: var ValidatorIndexInSyncCommittee)
+proc readValue*(reader: var JsonReader[RestJson], value: var IndexInSyncCommittee)
                {.raises: [IOError, SerializationError, Defect].} =
   let svalue = reader.readValue(string)
   let res = Base10.decode(uint64, svalue)
   if res.isOk():
     let v = res.get()
     if v < SYNC_COMMITTEE_SIZE:
-      value = ValidatorIndexInSyncCommittee(v)
+      value = IndexInSyncCommittee(v)
     else:
       reader.raiseUnexpectedValue(
-        "Validator index is bigger then SYNC_COMMITTEE_SIZE")
+        "Index in committee is bigger than SYNC_COMMITTEE_SIZE")
   else:
     reader.raiseUnexpectedValue($res.error())
 
diff --git a/beacon_chain/spec/eth2_apis/rest_types.nim b/beacon_chain/spec/eth2_apis/rest_types.nim
index bd670fecb..f18fc0185 100644
--- a/beacon_chain/spec/eth2_apis/rest_types.nim
+++ b/beacon_chain/spec/eth2_apis/rest_types.nim
@@ -105,7 +105,7 @@ type
   RestSyncCommitteeDuty* = object
     pubkey*: ValidatorPubKey
     validator_index*: ValidatorIndex
-    validator_sync_committee_indices*: seq[ValidatorIndexInSyncCommittee]
+    validator_sync_committee_indices*: seq[IndexInSyncCommittee]
 
   RestSyncCommitteeMessage* = object
     slot*: Slot