diff --git a/beacon_chain/beacon_node.nim b/beacon_chain/beacon_node.nim
index 622c591a2..cb1eeebb3 100644
--- a/beacon_chain/beacon_node.nim
+++ b/beacon_chain/beacon_node.nim
@@ -345,12 +345,13 @@ proc updateHead(node: BeaconNode, slot: Slot): BlockRef =
   newHead
 
 proc sendAttestation(node: BeaconNode,
+                     state: BeaconState,
                      validator: AttachedValidator,
                      attestationData: AttestationData,
                      committeeLen: int,
                      indexInCommittee: int) {.async.} =
   let
-    validatorSignature = await validator.signAttestation(attestationData)
+    validatorSignature = await validator.signAttestation(attestationData, state)
 
   var aggregationBits = CommitteeValidatorsBits.init(committeeLen)
   aggregationBits.raiseBit indexInCommittee
@@ -577,9 +578,9 @@ proc handleAttestations(node: BeaconNode, head: BlockRef, slot: Slot) =
           let ad = makeAttestationData(state, shard, blck.root)
           attestations.add((ad, committee.len, i, validator))
 
-  for a in attestations:
-    traceAsyncErrors sendAttestation(
-      node, a.validator, a.data, a.committeeLen, a.indexInCommittee)
+    for a in attestations:
+      traceAsyncErrors sendAttestation(
+        node, state, a.validator, a.data, a.committeeLen, a.indexInCommittee)
 
 proc handleProposal(node: BeaconNode, head: BlockRef, slot: Slot):
     Future[BlockRef] {.async.} =
diff --git a/beacon_chain/validator_pool.nim b/beacon_chain/validator_pool.nim
index af6f1848c..f64a0ffe2 100644
--- a/beacon_chain/validator_pool.nim
+++ b/beacon_chain/validator_pool.nim
@@ -37,7 +37,8 @@ proc signBlockProposal*(v: AttachedValidator, state: BeaconState, slot: Slot,
     discard
 
 proc signAttestation*(v: AttachedValidator,
-                      attestation: AttestationData): Future[ValidatorSig] {.async.} =
+                      attestation: AttestationData,
+                      state: BeaconState): Future[ValidatorSig] {.async.} =
   # TODO: implement this
   if v.kind == inProcess:
     await sleepAsync(chronos.milliseconds(1))
@@ -45,8 +46,11 @@ proc signAttestation*(v: AttachedValidator,
     let attestationRoot = hash_tree_root(attestation)
     # TODO: Avoid the allocations belows
     var dataToSign = @(attestationRoot.data) & @[0'u8]
-    # TODO: Use `domain` here
-    let domain = 0'u64
+    let domain = get_domain(
+      state,
+      DOMAIN_ATTESTATION,
+      attestation.target.epoch
+    )
     result = bls_sign(v.privKey, dataToSign, domain)
   else:
     # TODO: