diff --git a/beacon-chain/attestation/service_test.go b/beacon-chain/attestation/service_test.go
index 3e875e31b..ce3cd0fca 100644
--- a/beacon-chain/attestation/service_test.go
+++ b/beacon-chain/attestation/service_test.go
@@ -33,7 +33,7 @@ func TestUpdateLatestAttestation_UpdatesLatest(t *testing.T) {
 	service := NewAttestationService(context.Background(), &Config{BeaconDB: beaconDB})
 
 	attestation := &pb.Attestation{
-		AggregationBitfield: []byte{0x01},
+		AggregationBitfield: []byte{0x80},
 		Data: &pb.AttestationData{
 			Slot: 5,
 		},
@@ -72,7 +72,7 @@ func TestAttestationPool_UpdatesAttestationPool(t *testing.T) {
 
 	service := NewAttestationService(context.Background(), &Config{BeaconDB: beaconDB})
 	attestation := &pb.Attestation{
-		AggregationBitfield: []byte{0x01},
+		AggregationBitfield: []byte{0x80},
 		Data:                &pb.AttestationData{},
 	}
 
diff --git a/beacon-chain/core/epoch/epoch_operations_test.go b/beacon-chain/core/epoch/epoch_operations_test.go
index 3712157ac..095b2f9d0 100644
--- a/beacon-chain/core/epoch/epoch_operations_test.go
+++ b/beacon-chain/core/epoch/epoch_operations_test.go
@@ -345,7 +345,7 @@ func TestHeadAttestations_InvalidRange(t *testing.T) {
 func TestWinningRoot_AccurateRoot(t *testing.T) {
 	state := buildState(params.BeaconConfig().GenesisSlot, 100)
 	var participationBitfield []byte
-	participationBitfield = append(participationBitfield, byte(0x01))
+	participationBitfield = append(participationBitfield, byte(0x80))
 
 	// Generate 10 roots ([]byte{100}...[]byte{110})
 	var attestations []*pb.PendingAttestation
@@ -404,7 +404,7 @@ func TestAttestingValidators_MatchActive(t *testing.T) {
 				Slot:                    params.BeaconConfig().GenesisSlot,
 				CrosslinkDataRootHash32: []byte{byte(i + 100)},
 			},
-			AggregationBitfield: []byte{0x03},
+			AggregationBitfield: []byte{0xC0},
 		}
 		attestations = append(attestations, attestation)
 	}
@@ -455,7 +455,7 @@ func TestTotalAttestingBalance_CorrectBalance(t *testing.T) {
 				CrosslinkDataRootHash32: []byte{byte(i + 100)},
 			},
 			// All validators attested to the above roots.
-			AggregationBitfield: []byte{0x03},
+			AggregationBitfield: []byte{0xC0},
 		}
 		attestations = append(attestations, attestation)
 	}
diff --git a/beacon-chain/core/helpers/committee_test.go b/beacon-chain/core/helpers/committee_test.go
index 2f08893ca..9691e7a07 100644
--- a/beacon-chain/core/helpers/committee_test.go
+++ b/beacon-chain/core/helpers/committee_test.go
@@ -319,21 +319,21 @@ func TestAttestationParticipants_OK(t *testing.T) {
 			attestationSlot: params.BeaconConfig().GenesisSlot + 2,
 			stateSlot:       params.BeaconConfig().GenesisSlot + 5,
 			shard:           2,
-			bitfield:        []byte{0x03},
+			bitfield:        []byte{0xC0},
 			wanted:          []uint64{11, 121},
 		},
 		{
 			attestationSlot: params.BeaconConfig().GenesisSlot + 1,
 			stateSlot:       params.BeaconConfig().GenesisSlot + 10,
 			shard:           1,
-			bitfield:        []byte{0x01},
+			bitfield:        []byte{0x80},
 			wanted:          []uint64{4},
 		},
 		{
 			attestationSlot: params.BeaconConfig().GenesisSlot + 10,
 			stateSlot:       params.BeaconConfig().GenesisSlot + 10,
 			shard:           10,
-			bitfield:        []byte{0x03},
+			bitfield:        []byte{0xC0},
 			wanted:          []uint64{14, 30},
 		},
 	}
@@ -381,7 +381,7 @@ func TestAttestationParticipants_IncorrectBitfield(t *testing.T) {
 }
 
 func TestVerifyBitfield_OK(t *testing.T) {
-	bitfield := []byte{0xff}
+	bitfield := []byte{0xFF}
 	committeeSize := 8
 
 	isValidated, err := VerifyBitfield(bitfield, committeeSize)
@@ -393,7 +393,7 @@ func TestVerifyBitfield_OK(t *testing.T) {
 		t.Error("bitfield is not validated when it was supposed to be")
 	}
 
-	bitfield = []byte{0xff, 0x80}
+	bitfield = []byte{0xff, 0x01}
 	committeeSize = 9
 
 	isValidated, err = VerifyBitfield(bitfield, committeeSize)
@@ -405,7 +405,7 @@ func TestVerifyBitfield_OK(t *testing.T) {
 		t.Error("bitfield is validated when it was supposed to be")
 	}
 
-	bitfield = []byte{0xff, 0x01}
+	bitfield = []byte{0xff, 0x80}
 	committeeSize = 10
 	isValidated, err = VerifyBitfield(bitfield, committeeSize)
 	if err != nil {
diff --git a/beacon-chain/core/validators/validator_test.go b/beacon-chain/core/validators/validator_test.go
index ccedb6db8..7339be593 100644
--- a/beacon-chain/core/validators/validator_test.go
+++ b/beacon-chain/core/validators/validator_test.go
@@ -67,9 +67,9 @@ func TestBoundaryAttesterIndices_OK(t *testing.T) {
 
 	boundaryAttestations := []*pb.PendingAttestation{
 		{Data: &pb.AttestationData{Slot: params.BeaconConfig().GenesisSlot},
-			AggregationBitfield: []byte{0x03}}, // returns indices 242
+			AggregationBitfield: []byte{0xC0}}, // returns indices 242
 		{Data: &pb.AttestationData{Slot: params.BeaconConfig().GenesisSlot},
-			AggregationBitfield: []byte{0x03}}, // returns indices 237,224,2
+			AggregationBitfield: []byte{0xC0}}, // returns indices 237,224,2
 	}
 
 	attesterIndices, err := ValidatorIndices(context.Background(), state, boundaryAttestations)
@@ -119,9 +119,9 @@ func TestAttestingValidatorIndices_OK(t *testing.T) {
 		t.Fatalf("Could not execute AttestingValidatorIndices: %v", err)
 	}
 
-	if !reflect.DeepEqual(indices, []uint64{1117, 333}) {
+	if !reflect.DeepEqual(indices, []uint64{1141, 688}) {
 		t.Errorf("Could not get incorrect validator indices. Wanted: %v, got: %v",
-			[]uint64{1117, 333}, indices)
+			[]uint64{1141, 688}, indices)
 	}
 }
 
diff --git a/shared/bitutil/BUILD.bazel b/shared/bitutil/BUILD.bazel
index 6989adf06..f0f7b9a51 100644
--- a/shared/bitutil/BUILD.bazel
+++ b/shared/bitutil/BUILD.bazel
@@ -5,7 +5,10 @@ go_library(
     srcs = ["bit.go"],
     importpath = "github.com/prysmaticlabs/prysm/shared/bitutil",
     visibility = ["//visibility:public"],
-    deps = ["@com_github_steakknife_hamming//:go_default_library"],
+    deps = [
+        "//shared/mathutil:go_default_library",
+        "@com_github_steakknife_hamming//:go_default_library",
+    ],
 )
 
 go_test(
diff --git a/shared/bitutil/bit.go b/shared/bitutil/bit.go
index aa3200d71..94312366f 100644
--- a/shared/bitutil/bit.go
+++ b/shared/bitutil/bit.go
@@ -2,7 +2,8 @@ package bitutil
 
 import (
 	"fmt"
-	"math"
+
+	"github.com/prysmaticlabs/prysm/shared/mathutil"
 
 	"github.com/steakknife/hamming"
 )
@@ -22,7 +23,7 @@ func CheckBit(bitfield []byte, index int) (bool, error) {
 			len(bitfield), chunkLocation-1)
 	}
 
-	field := bitfield[chunkLocation-1] >> uint(indexLocation-1)
+	field := bitfield[chunkLocation-1] >> (7 - uint(indexLocation-1))
 	return field%2 != 0, nil
 }
 
@@ -40,7 +41,7 @@ func BitLength(b int) int {
 // SetBitfield takes an index and returns bitfield with the index flipped.
 func SetBitfield(index int) []byte {
 	chunkLocation := index / 8
-	indexLocation := math.Pow(2, 7-float64(index%8))
+	indexLocation := mathutil.PowerOf2(uint64(7 - (index % 8)))
 	var bitfield []byte
 
 	for i := 0; i < chunkLocation; i++ {
diff --git a/shared/bitutil/bit_test.go b/shared/bitutil/bit_test.go
index 34ef542f1..f7913fc1f 100644
--- a/shared/bitutil/bit_test.go
+++ b/shared/bitutil/bit_test.go
@@ -11,9 +11,9 @@ func TestCheckBit(t *testing.T) {
 		b int
 		c bool
 	}{
-		{a: []byte{200}, b: 3, c: true},   //11001000
-		{a: []byte{148}, b: 2, c: true},   //10010100
-		{a: []byte{146}, b: 3, c: false},  //10010010
+		{a: []byte{200}, b: 4, c: true},   //11001000
+		{a: []byte{148}, b: 3, c: true},   //10010100
+		{a: []byte{146}, b: 7, c: false},  //10010010
 		{a: []byte{179}, b: 0, c: true},   //10110011
 		{a: []byte{49}, b: 1, c: false},   //00110001
 		{a: []byte{49}, b: 100, c: false}, //00110001
diff --git a/validator/client/validator_attest.go b/validator/client/validator_attest.go
index 53ca426d2..b84967aab 100644
--- a/validator/client/validator_attest.go
+++ b/validator/client/validator_attest.go
@@ -97,7 +97,17 @@ func (v *validator) AttestToBlockHead(ctx context.Context, slot uint64) {
 	// Note: calling get_attestation_participants(state, attestation.data, attestation.aggregation_bitfield)
 	// should return a list of length equal to 1, containing validator_index.
 
-	aggregationBitfield := bitutil.SetBitfield(int(validatorIndexRes.Index))
+	// Find the index in committee to be used for
+	// the aggregation bitfield
+	var indexInCommittee int
+	for i, vIndex := range resp.Committee {
+		if vIndex == validatorIndexRes.Index {
+			indexInCommittee = i
+			break
+		}
+	}
+
+	aggregationBitfield := bitutil.SetBitfield(indexInCommittee)
 	attestation.AggregationBitfield = aggregationBitfield
 
 	// TODO(#1366): Use BLS to generate an aggregate signature.
diff --git a/validator/client/validator_attest_test.go b/validator/client/validator_attest_test.go
index f18c139aa..cfa86c418 100644
--- a/validator/client/validator_attest_test.go
+++ b/validator/client/validator_attest_test.go
@@ -115,7 +115,7 @@ func TestAttestToBlockHead_AttestsCorrectly(t *testing.T) {
 
 	validator, m, finish := setup(t)
 	defer finish()
-	validatorIndex := uint64(4)
+	validatorIndex := uint64(7)
 	committee := []uint64{0, 3, 4, 2, validatorIndex, 6, 8, 9, 10}
 	m.validatorClient.EXPECT().ValidatorIndex(
 		gomock.Any(), // ctx
@@ -166,7 +166,7 @@ func TestAttestToBlockHead_AttestsCorrectly(t *testing.T) {
 		CustodyBitfield:    make([]byte, (len(committee)+7)/8),
 		AggregateSignature: []byte("signed"),
 	}
-	aggregationBitfield := bitutil.SetBitfield(int(validatorIndex))
+	aggregationBitfield := bitutil.SetBitfield(4)
 	expectedAttestation.AggregationBitfield = aggregationBitfield
 	if !proto.Equal(generatedAttestation, expectedAttestation) {
 		t.Errorf("Incorrectly attested head, wanted %v, received %v", expectedAttestation, generatedAttestation)