diff --git a/api/v1/deneb/generate.go b/api/v1/deneb/generate.go
index 2546891f..d5e1a9f7 100644
--- a/api/v1/deneb/generate.go
+++ b/api/v1/deneb/generate.go
@@ -14,6 +14,6 @@
 package deneb
 
 // Need to `go install github.com/ferranbt/fastssz/sszgen@latest` for this to work.
-//go:generate rm -f blindedbeaconblock_ssz.go blindedbeaconblockbody_ssz.go blindedblobsidecar_ssz.go blindedblockcontents_ssz.go blockcontents_ssz.go signedblindedbeaconblock_ssz.go signedblindedblockcontents_ssz.go signedblockcontents_ssz.go
-//go:generate sszgen --include ../../../spec/phase0,../../../spec/altair,../../../spec/bellatrix,../../../spec/capella,../../../spec/deneb -path . --suffix ssz -objs BlindedBeaconBlock,BlindedBeaconBlockBody,BlindedBlobSidecar,BlindedBlockContents,BlockContents,SignedBlindedBeaconBlock,SignedBlindedBlockContents,SignedBlockContents
-//go:generate goimports -w blindedbeaconblock_ssz.go blindedbeaconblockbody_ssz.go blindedblobsidecar_ssz.go blindedblockcontents_ssz.go blockcontents_ssz.go signedblindedbeaconblock_ssz.go signedblindedblockcontents_ssz.go,signedblockcontents_ssz.go
+//go:generate rm -f blindedbeaconblock_ssz.go blindedbeaconblockbody_ssz.go blockcontents_ssz.go signedblindedbeaconblock_ssz.go signedblockcontents_ssz.go
+//go:generate sszgen --include ../../../spec/phase0,../../../spec/altair,../../../spec/bellatrix,../../../spec/capella,../../../spec/deneb -path . --suffix ssz -objs BlindedBeaconBlock,BlindedBeaconBlockBody,BlockContents,SignedBlindedBeaconBlock,SignedBlockContents
+//go:generate goimports -w blindedbeaconblock_ssz.go blindedbeaconblockbody_ssz.go blockcontents_ssz.go signedblindedbeaconblock_ssz.go signedblockcontents_ssz.go
diff --git a/spec/phase0/attestation.go b/spec/phase0/attestation.go
index e87cdf38..e9c5715c 100644
--- a/spec/phase0/attestation.go
+++ b/spec/phase0/attestation.go
@@ -72,7 +72,7 @@ func (a *Attestation) unpack(attestationJSON *attestationJSON) error {
 		return errors.New("aggregation bits missing")
 	}
 	if a.AggregationBits, err = hex.DecodeString(strings.TrimPrefix(attestationJSON.AggregationBits, "0x")); err != nil {
-		return errors.Wrap(err, "invalid value for beacon block root")
+		return errors.Wrap(err, "invalid value for aggregation bits")
 	}
 	a.Data = attestationJSON.Data
 	if a.Data == nil {
diff --git a/spec/phase0/attestation_test.go b/spec/phase0/attestation_test.go
index cdfd6926..162c2bde 100644
--- a/spec/phase0/attestation_test.go
+++ b/spec/phase0/attestation_test.go
@@ -52,7 +52,7 @@ func TestAttestationJSON(t *testing.T) {
 		{
 			name:  "AggregationBitsInvalid",
 			input: []byte(`{"aggregation_bits":"invalid","data":{"slot":"100","index":"1","beacon_block_root":"0x000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f","source":{"epoch":"1","root":"0x202122232425262728292a2b2c2d2e2f303132333435363738393a3b3c3d3e3f"},"target":{"epoch":"2","root":"0x404142434445464748494a4b4c4d4e4f505152535455565758595a5b5c5d5e5f"}},"signature":"0x606162636465666768696a6b6c6d6e6f707172737475767778797a7b7c7d7e7f808182838485868788898a8b8c8d8e8f909192939495969798999a9b9c9d9e9fa0a1a2a3a4a5a6a7a8a9aaabacadaeafb0b1b2b3b4b5b6b7b8b9babbbcbdbebf"}`),
-			err:   "invalid value for beacon block root: encoding/hex: invalid byte: U+0069 'i'",
+			err:   "invalid value for aggregation bits: encoding/hex: invalid byte: U+0069 'i'",
 		},
 		{
 			name:  "DataMissing",
diff --git a/spec/phase0/types.go b/spec/phase0/types.go
index 1b7d6d57..74954a66 100644
--- a/spec/phase0/types.go
+++ b/spec/phase0/types.go
@@ -29,6 +29,9 @@ func (e *Epoch) UnmarshalJSON(input []byte) error {
 	if len(input) == 0 {
 		return errors.New("input missing")
 	}
+	if len(input) < 3 {
+		return errors.New("input malformed")
+	}
 
 	if !bytes.HasPrefix(input, []byte{'"'}) {
 		return errors.New("invalid prefix")
@@ -47,7 +50,7 @@ func (e *Epoch) UnmarshalJSON(input []byte) error {
 }
 
 // MarshalJSON implements json.Marshaler.
-func (e *Epoch) MarshalJSON() ([]byte, error) {
+func (e Epoch) MarshalJSON() ([]byte, error) {
 	return []byte(fmt.Sprintf(`"%d"`, e)), nil
 }