diff --git a/beacon_chain/gossip_processing/eth2_processor.nim b/beacon_chain/gossip_processing/eth2_processor.nim
index bd8c57d74..e1a696ecb 100644
--- a/beacon_chain/gossip_processing/eth2_processor.nim
+++ b/beacon_chain/gossip_processing/eth2_processor.nim
@@ -188,11 +188,11 @@ proc checkForPotentialDoppelganger(
 proc attestationValidator*(
     self: ref Eth2Processor,
     attestation: Attestation,
-    committeeIndex: uint64,
+    attestation_subnet: uint64,
     checksExpensive: bool = true): Future[ValidationResult] {.async.} =
   logScope:
     attestation = shortLog(attestation)
-    committeeIndex
+    attestation_subnet
 
   let
     wallTime = self.getWallTime()
@@ -211,7 +211,7 @@ proc attestationValidator*(
   # Now proceed to validation
   let v = await self.attestationPool.validateAttestation(
       self.batchCrypto,
-      attestation, wallTime, committeeIndex, checksExpensive)
+      attestation, wallTime, attestation_subnet, checksExpensive)
   if v.isErr():
     debug "Dropping attestation", err = v.error()
     return v.error[0]
diff --git a/beacon_chain/gossip_processing/gossip_validation.nim b/beacon_chain/gossip_processing/gossip_validation.nim
index 33d2a3f05..564cdff74 100644
--- a/beacon_chain/gossip_processing/gossip_validation.nim
+++ b/beacon_chain/gossip_processing/gossip_validation.nim
@@ -134,16 +134,16 @@ func check_aggregation_count(
 
 func check_attestation_subnet(
     epochRef: EpochRef, attestation: Attestation,
-    topicCommitteeIndex: uint64): Result[void, (ValidationResult, cstring)] =
+    attestation_subnet: uint64): Result[void, (ValidationResult, cstring)] =
   let
     expectedSubnet =
       compute_subnet_for_attestation(
         get_committee_count_per_slot(epochRef),
         attestation.data.slot, attestation.data.index.CommitteeIndex)
 
-  if expectedSubnet != topicCommitteeIndex:
+  if expectedSubnet != attestation_subnet:
     return err((ValidationResult.Reject, cstring(
-      "Attestation's committee index not for the correct subnet")))
+      "Attestation not on the correct subnet")))
 
   ok()
 
@@ -157,7 +157,7 @@ proc validateAttestation*(
     batchCrypto: ref BatchCrypto,
     attestation: Attestation,
     wallTime: BeaconTime,
-    topicCommitteeIndex: uint64, checksExpensive: bool):
+    attestation_subnet: uint64, checksExpensive: bool):
     Future[Result[tuple[attestingIndices: seq[ValidatorIndex], sig: CookedSig],
       (ValidationResult, cstring)]] {.async.} =
   # Some of the checks below have been reordered compared to the spec, to
@@ -227,7 +227,7 @@ proc validateAttestation*(
   # attestation.data.target.epoch), which may be pre-computed along with the
   # committee information for the signature check.
   block:
-    let v = check_attestation_subnet(epochRef, attestation, topicCommitteeIndex) # [REJECT]
+    let v = check_attestation_subnet(epochRef, attestation, attestation_subnet) # [REJECT]
     if v.isErr():
       return err(v.error)
 
diff --git a/beacon_chain/nimbus_beacon_node.nim b/beacon_chain/nimbus_beacon_node.nim
index 425e3d7c4..450a2836a 100644
--- a/beacon_chain/nimbus_beacon_node.nim
+++ b/beacon_chain/nimbus_beacon_node.nim
@@ -1204,12 +1204,12 @@ proc installMessageValidators(node: BeaconNode) =
   # subnets are subscribed to during any given epoch.
   for it in 0'u64 ..< ATTESTATION_SUBNET_COUNT.uint64:
     closureScope:
-      let ci = it
+      let attestation_subnet = it
       node.network.addAsyncValidator(
-        getAttestationTopic(node.forkDigest, ci),
+        getAttestationTopic(node.forkDigest, attestation_subnet),
         # This proc needs to be within closureScope; don't lift out of loop.
         proc(attestation: Attestation): Future[ValidationResult] =
-          node.processor.attestationValidator(attestation, ci))
+          node.processor.attestationValidator(attestation, attestation_subnet))
 
   node.network.addAsyncValidator(
     getAggregateAndProofsTopic(node.forkDigest),
diff --git a/beacon_chain/rpc/validator_api.nim b/beacon_chain/rpc/validator_api.nim
index 6e1ae71d4..30508e8ae 100644
--- a/beacon_chain/rpc/validator_api.nim
+++ b/beacon_chain/rpc/validator_api.nim
@@ -122,7 +122,7 @@ proc installValidatorApiHandlers*(rpcServer: RpcServer, node: BeaconNode) {.
       validator_pubkey: ValidatorPubKey, slot_signature: ValidatorSig) -> bool:
     debug "post_v1_validator_beacon_committee_subscriptions",
       committee_index, slot
-    if committee_index.uint64 >= ATTESTATION_SUBNET_COUNT.uint64:
+    if committee_index.uint64 >= MAX_COMMITTEES_PER_SLOT.uint64:
       raise newException(CatchableError,
         "Invalid committee index")
 
diff --git a/beacon_chain/rpc/validator_rest_api.nim b/beacon_chain/rpc/validator_rest_api.nim
index 93a705b71..b2f795bd6 100644
--- a/beacon_chain/rpc/validator_rest_api.nim
+++ b/beacon_chain/rpc/validator_rest_api.nim
@@ -355,7 +355,7 @@ proc installValidatorApiHandlers*(router: var RestRouter, node: BeaconNode) =
       return RestApiResponse.jsonError(Http503, BeaconNodeInSyncError)
 
     for request in requests:
-      if uint64(request.committee_index) >= uint64(ATTESTATION_SUBNET_COUNT):
+      if uint64(request.committee_index) >= uint64(MAX_COMMITTEES_PER_SLOT):
         return RestApiResponse.jsonError(Http400,
                                          InvalidCommitteeIndexValueError)
       let validator_pubkey =