diff --git a/types/priv_validator.go b/types/priv_validator.go
index 5dfd521f..31c65eeb 100644
--- a/types/priv_validator.go
+++ b/types/priv_validator.go
@@ -8,6 +8,7 @@ import (
 	"io/ioutil"
 	"os"
 	"sync"
+	"time"
 
 	crypto "github.com/tendermint/go-crypto"
 	data "github.com/tendermint/go-wire/data"
@@ -193,12 +194,13 @@ func (privVal *PrivValidatorFS) Reset() {
 	privVal.Save()
 }
 
-// SignVote signs a canonical representation of the vote, along with the chainID.
-// Implements PrivValidator.
+// SignVote signs a canonical representation of the vote, along with the
+// chainID. Implements PrivValidator.
 func (privVal *PrivValidatorFS) SignVote(chainID string, vote *Vote) error {
 	privVal.mtx.Lock()
 	defer privVal.mtx.Unlock()
-	signature, err := privVal.signBytesHRS(vote.Height, vote.Round, voteToStep(vote), SignBytes(chainID, vote))
+	signature, err := privVal.signBytesHRS(vote.Height, vote.Round, voteToStep(vote),
+		SignBytes(chainID, vote), checkVotesOnlyDifferByTimestamp)
 	if err != nil {
 		return errors.New(cmn.Fmt("Error signing vote: %v", err))
 	}
@@ -206,12 +208,13 @@ func (privVal *PrivValidatorFS) SignVote(chainID string, vote *Vote) error {
 	return nil
 }
 
-// SignProposal signs a canonical representation of the proposal, along with the chainID.
-// Implements PrivValidator.
+// SignProposal signs a canonical representation of the proposal, along with
+// the chainID. Implements PrivValidator.
 func (privVal *PrivValidatorFS) SignProposal(chainID string, proposal *Proposal) error {
 	privVal.mtx.Lock()
 	defer privVal.mtx.Unlock()
-	signature, err := privVal.signBytesHRS(proposal.Height, proposal.Round, stepPropose, SignBytes(chainID, proposal))
+	signature, err := privVal.signBytesHRS(proposal.Height, proposal.Round, stepPropose,
+		SignBytes(chainID, proposal), checkProposalsOnlyDifferByTimestamp)
 	if err != nil {
 		return fmt.Errorf("Error signing proposal: %v", err)
 	}
@@ -219,59 +222,76 @@ func (privVal *PrivValidatorFS) SignProposal(chainID string, proposal *Proposal)
 	return nil
 }
 
-// signBytesHRS signs the given signBytes if the height/round/step (HRS)
-// are greater than the latest state. If the HRS are equal,
-// it returns the privValidator.LastSignature.
-func (privVal *PrivValidatorFS) signBytesHRS(height int64, round int, step int8, signBytes []byte) (crypto.Signature, error) {
-
-	sig := crypto.Signature{}
-	// If height regression, err
+// returns error if HRS regression or no LastSignBytes. returns true if HRS is unchanged
+func (privVal *PrivValidatorFS) checkHRS(height int64, round int, step int8) (bool, error) {
 	if privVal.LastHeight > height {
-		return sig, errors.New("Height regression")
+		return false, errors.New("Height regression")
 	}
-	// More cases for when the height matches
+
 	if privVal.LastHeight == height {
-		// If round regression, err
 		if privVal.LastRound > round {
-			return sig, errors.New("Round regression")
+			return false, errors.New("Round regression")
 		}
-		// If step regression, err
+
 		if privVal.LastRound == round {
 			if privVal.LastStep > step {
-				return sig, errors.New("Step regression")
+				return false, errors.New("Step regression")
 			} else if privVal.LastStep == step {
 				if privVal.LastSignBytes != nil {
 					if privVal.LastSignature.Empty() {
-						cmn.PanicSanity("privVal: LastSignature is nil but LastSignBytes is not!")
-					}
-					// so we dont sign a conflicting vote or proposal
-					// NOTE: proposals are non-deterministic (include time),
-					// so we can actually lose them, but will still never sign conflicting ones
-					if bytes.Equal(privVal.LastSignBytes, signBytes) {
-						// log.Notice("Using privVal.LastSignature", "sig", privVal.LastSignature)
-						return privVal.LastSignature, nil
+						panic("privVal: LastSignature is nil but LastSignBytes is not!")
 					}
+					return true, nil
 				}
-				return sig, errors.New("Step regression")
+				return false, errors.New("No LastSignature found")
 			}
 		}
 	}
+	return false, nil
+}
 
-	// Sign
-	sig, err := privVal.Sign(signBytes)
+// signBytesHRS signs the given signBytes if the height/round/step (HRS) are
+// greater than the latest state. If the HRS are equal and the only thing changed is the timestamp,
+// it returns the privValidator.LastSignature. Else it returns an error.
+func (privVal *PrivValidatorFS) signBytesHRS(height int64, round int, step int8,
+	signBytes []byte, checkFn checkOnlyDifferByTimestamp) (crypto.Signature, error) {
+	sig := crypto.Signature{}
+
+	sameHRS, err := privVal.checkHRS(height, round, step)
 	if err != nil {
 		return sig, err
 	}
 
-	// Persist height/round/step
+	// We might crash before writing to the wal,
+	// causing us to try to re-sign for the same HRS
+	if sameHRS {
+		// if they're the same or only differ by timestamp,
+		// return the LastSignature. Otherwise, error
+		if bytes.Equal(signBytes, privVal.LastSignBytes) ||
+			checkFn(privVal.LastSignBytes, signBytes) {
+			return privVal.LastSignature, nil
+		}
+		return sig, fmt.Errorf("Conflicting data")
+	}
+
+	sig, err = privVal.Sign(signBytes)
+	if err != nil {
+		return sig, err
+	}
+	privVal.saveSigned(height, round, step, signBytes, sig)
+	return sig, nil
+}
+
+// Persist height/round/step and signature
+func (privVal *PrivValidatorFS) saveSigned(height int64, round int, step int8,
+	signBytes []byte, sig crypto.Signature) {
+
 	privVal.LastHeight = height
 	privVal.LastRound = round
 	privVal.LastStep = step
 	privVal.LastSignature = sig
 	privVal.LastSignBytes = signBytes
 	privVal.save()
-
-	return sig, nil
 }
 
 // SignHeartbeat signs a canonical representation of the heartbeat, along with the chainID.
@@ -306,3 +326,47 @@ func (pvs PrivValidatorsByAddress) Swap(i, j int) {
 	pvs[i] = pvs[j]
 	pvs[j] = it
 }
+
+//-------------------------------------
+
+type checkOnlyDifferByTimestamp func([]byte, []byte) bool
+
+// returns true if the only difference in the votes is their timestamp
+func checkVotesOnlyDifferByTimestamp(lastSignBytes, newSignBytes []byte) bool {
+	var lastVote, newVote CanonicalJSONOnceVote
+	if err := json.Unmarshal(lastSignBytes, &lastVote); err != nil {
+		panic(fmt.Sprintf("LastSignBytes cannot be unmarshalled into vote: %v", err))
+	}
+	if err := json.Unmarshal(newSignBytes, &newVote); err != nil {
+		panic(fmt.Sprintf("signBytes cannot be unmarshalled into vote: %v", err))
+	}
+
+	// set the times to the same value and check equality
+	now := CanonicalTime(time.Now())
+	lastVote.Vote.Timestamp = now
+	newVote.Vote.Timestamp = now
+	lastVoteBytes, _ := json.Marshal(lastVote)
+	newVoteBytes, _ := json.Marshal(newVote)
+
+	return bytes.Equal(newVoteBytes, lastVoteBytes)
+}
+
+// returns true if the only difference in the proposals is their timestamp
+func checkProposalsOnlyDifferByTimestamp(lastSignBytes, newSignBytes []byte) bool {
+	var lastProposal, newProposal CanonicalJSONOnceProposal
+	if err := json.Unmarshal(lastSignBytes, &lastProposal); err != nil {
+		panic(fmt.Sprintf("LastSignBytes cannot be unmarshalled into proposal: %v", err))
+	}
+	if err := json.Unmarshal(newSignBytes, &newProposal); err != nil {
+		panic(fmt.Sprintf("signBytes cannot be unmarshalled into proposal: %v", err))
+	}
+
+	// set the times to the same value and check equality
+	now := CanonicalTime(time.Now())
+	lastProposal.Proposal.Timestamp = now
+	newProposal.Proposal.Timestamp = now
+	lastProposalBytes, _ := json.Marshal(lastProposal)
+	newProposalBytes, _ := json.Marshal(newProposal)
+
+	return bytes.Equal(newProposalBytes, lastProposalBytes)
+}
diff --git a/types/priv_validator_test.go b/types/priv_validator_test.go
index 4e55fd49..2fefee60 100644
--- a/types/priv_validator_test.go
+++ b/types/priv_validator_test.go
@@ -124,6 +124,13 @@ func TestSignVote(t *testing.T) {
 		err = privVal.SignVote("mychainid", c)
 		assert.Error(err, "expected error on signing conflicting vote")
 	}
+
+	// try signing a vote with a different time stamp
+	sig := vote.Signature
+	vote.Timestamp = vote.Timestamp.Add(time.Duration(1000))
+	err = privVal.SignVote("mychainid", vote)
+	assert.NoError(err)
+	assert.Equal(sig, vote.Signature)
 }
 
 func TestSignProposal(t *testing.T) {
@@ -157,6 +164,13 @@ func TestSignProposal(t *testing.T) {
 		err = privVal.SignProposal("mychainid", c)
 		assert.Error(err, "expected error on signing conflicting proposal")
 	}
+
+	// try signing a proposal with a different time stamp
+	sig := proposal.Signature
+	proposal.Timestamp = proposal.Timestamp.Add(time.Duration(1000))
+	err = privVal.SignProposal("mychainid", proposal)
+	assert.NoError(err)
+	assert.Equal(sig, proposal.Signature)
 }
 
 func newVote(addr data.Bytes, idx int, height int64, round int, typ byte, blockID BlockID) *Vote {