diff --git a/types/block.go b/types/block.go
index 4c91c5fe1..461782fd8 100644
--- a/types/block.go
+++ b/types/block.go
@@ -420,7 +420,7 @@ func (data *Data) StringIndented(indent string) string {
 
 // BlockID defines the unique ID of a block as its Hash and its PartSetHeader
 type BlockID struct {
-	Hash        data.Bytes    `json:"hash"`
+	Hash        data.Bytes    `json:"hash,omitempty"`
 	PartsHeader PartSetHeader `json:"parts"`
 }
 
diff --git a/types/canonical_json.go b/types/canonical_json.go
index a2e91164f..be371f242 100644
--- a/types/canonical_json.go
+++ b/types/canonical_json.go
@@ -22,6 +22,7 @@ type CanonicalJSONProposal struct {
 	POLBlockID       CanonicalJSONBlockID       `json:"pol_block_id"`
 	POLRound         int                        `json:"pol_round"`
 	Round            int                        `json:"round"`
+	Timestamp        string                     `json:"timestamp"`
 }
 
 type CanonicalJSONVote struct {
@@ -78,6 +79,7 @@ func CanonicalProposal(proposal *Proposal) CanonicalJSONProposal {
 	return CanonicalJSONProposal{
 		BlockPartsHeader: CanonicalPartSetHeader(proposal.BlockPartsHeader),
 		Height:           proposal.Height,
+		Timestamp:        proposal.TimeString(),
 		POLBlockID:       CanonicalBlockID(proposal.POLBlockID),
 		POLRound:         proposal.POLRound,
 		Round:            proposal.Round,
diff --git a/types/proposal.go b/types/proposal.go
index 93e788961..58dfa0944 100644
--- a/types/proposal.go
+++ b/types/proposal.go
@@ -4,6 +4,7 @@ import (
 	"errors"
 	"fmt"
 	"io"
+	"time"
 
 	"github.com/tendermint/go-crypto"
 	"github.com/tendermint/go-wire"
@@ -14,6 +15,9 @@ var (
 	ErrInvalidBlockPartHash      = errors.New("Error invalid block part hash")
 )
 
+// TimeFormat is RFC3339Millis, used for generating the sigs
+const TimeFormat = "2006-01-02T15:04:05.999Z07:00"
+
 // Proposal defines a block proposal for the consensus.
 // It refers to the block only by its PartSetHeader.
 // It must be signed by the correct proposer for the given Height/Round
@@ -22,6 +26,7 @@ var (
 type Proposal struct {
 	Height           int64            `json:"height"`
 	Round            int              `json:"round"`
+	Timestamp        time.Time        `json:"timestamp"`
 	BlockPartsHeader PartSetHeader    `json:"block_parts_header"`
 	POLRound         int              `json:"pol_round"`    // -1 if null.
 	POLBlockID       BlockID          `json:"pol_block_id"` // zero if null.
@@ -34,16 +39,23 @@ func NewProposal(height int64, round int, blockPartsHeader PartSetHeader, polRou
 	return &Proposal{
 		Height:           height,
 		Round:            round,
+		Timestamp:        time.Now().UTC(),
 		BlockPartsHeader: blockPartsHeader,
 		POLRound:         polRound,
 		POLBlockID:       polBlockID,
 	}
 }
 
+// TimeString returns the canonical encoding of timestamp
+func (p *Proposal) TimeString() string {
+	return p.Timestamp.Format(TimeFormat)
+}
+
 // String returns a string representation of the Proposal.
 func (p *Proposal) String() string {
-	return fmt.Sprintf("Proposal{%v/%v %v (%v,%v) %v}", p.Height, p.Round,
-		p.BlockPartsHeader, p.POLRound, p.POLBlockID, p.Signature)
+	return fmt.Sprintf("Proposal{%v/%v %v (%v,%v) %v @ %s}",
+		p.Height, p.Round, p.BlockPartsHeader, p.POLRound,
+		p.POLBlockID, p.Signature, p.TimeString())
 }
 
 // WriteSignBytes writes the Proposal bytes for signing
diff --git a/types/proposal_test.go b/types/proposal_test.go
index 352ba8de1..c2e62f258 100644
--- a/types/proposal_test.go
+++ b/types/proposal_test.go
@@ -2,20 +2,30 @@ package types
 
 import (
 	"testing"
+	"time"
 )
 
-var testProposal = &Proposal{
-	Height:           12345,
-	Round:            23456,
-	BlockPartsHeader: PartSetHeader{111, []byte("blockparts")},
-	POLRound:         -1,
+var testProposal *Proposal
+
+func init() {
+	var stamp, err = time.Parse(TimeFormat, "2018-02-11T07:09:22.765Z")
+	if err != nil {
+		panic(err)
+	}
+	testProposal = &Proposal{
+		Height:           12345,
+		Round:            23456,
+		BlockPartsHeader: PartSetHeader{111, []byte("blockparts")},
+		POLRound:         -1,
+		Timestamp:        stamp,
+	}
 }
 
 func TestProposalSignable(t *testing.T) {
 	signBytes := SignBytes("test_chain_id", testProposal)
 	signStr := string(signBytes)
 
-	expected := `{"chain_id":"test_chain_id","proposal":{"block_parts_header":{"hash":"626C6F636B7061727473","total":111},"height":12345,"pol_block_id":{},"pol_round":-1,"round":23456}}`
+	expected := `{"chain_id":"test_chain_id","proposal":{"block_parts_header":{"hash":"626C6F636B7061727473","total":111},"height":12345,"pol_block_id":{},"pol_round":-1,"round":23456,"timestamp":"2018-02-11T07:09:22.765Z"}}`
 	if signStr != expected {
 		t.Errorf("Got unexpected sign string for Proposal. Expected:\n%v\nGot:\n%v", expected, signStr)
 	}