diff --git a/CHANGELOG.md b/CHANGELOG.md
index 07165ada9..5b1cd54e3 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -25,6 +25,7 @@ BREAKING CHANGES:
 - Introduce EventDataInner for serializing events
 - remove all use of go-wire around user interfaces
 - rpc responses no longer have type information :)
+- [types] Do not include the `Accum` field when computing the hash of a validator. This makes the ValidatorSetHash unique for a given validator set, rather than changing with every block (as the Accum changes)
 
 
 FEATURES:
diff --git a/types/validator.go b/types/validator.go
index 595c52ff1..0c782321e 100644
--- a/types/validator.go
+++ b/types/validator.go
@@ -12,13 +12,14 @@ import (
 )
 
 // Volatile state for each Validator
-// TODO: make non-volatile identity
-// 	- Remove Accum - it can be computed, and now valset becomes identifying
+// NOTE: The Accum is not included in Validator.Hash();
+// make sure to update that method if changes are made here
 type Validator struct {
 	Address     data.Bytes    `json:"address"`
 	PubKey      crypto.PubKey `json:"pub_key"`
 	VotingPower int64         `json:"voting_power"`
-	Accum       int64         `json:"accum"`
+
+	Accum int64 `json:"accum"`
 }
 
 func NewValidator(pubKey crypto.PubKey, votingPower int64) *Validator {
@@ -69,8 +70,18 @@ func (v *Validator) String() string {
 		v.Accum)
 }
 
+// Hash computes the unique ID of a validator with a given voting power.
+// It exludes the Accum value, which changes with every round.
 func (v *Validator) Hash() []byte {
-	return wire.BinaryRipemd160(v)
+	return wire.BinaryRipemd160(struct {
+		Address     data.Bytes
+		PubKey      crypto.PubKey
+		VotingPower int64
+	}{
+		v.Address,
+		v.PubKey,
+		v.VotingPower,
+	})
 }
 
 //-------------------------------------
diff --git a/types/validator_set.go b/types/validator_set.go
index 214e073d0..b374df576 100644
--- a/types/validator_set.go
+++ b/types/validator_set.go
@@ -21,7 +21,6 @@ import (
 // NOTE: Not goroutine-safe.
 // NOTE: All get/set to validators should copy the value for safety.
 // TODO: consider validator Accum overflow
-// TODO: move valset into an iavl tree where key is 'blockbonded|pubkey'
 type ValidatorSet struct {
 	// NOTE: persisted via reflect, must be exported.
 	Validators []*Validator `json:"validators"`
diff --git a/types/vote_set_test.go b/types/vote_set_test.go
index 6ef075927..84e13ac17 100644
--- a/types/vote_set_test.go
+++ b/types/vote_set_test.go
@@ -11,7 +11,6 @@ import (
 )
 
 // NOTE: privValidators are in order
-// TODO: Move it out?
 func randVoteSet(height int, round int, type_ byte, numValidators int, votingPower int64) (*VoteSet, *ValidatorSet, []*PrivValidator) {
 	valSet, privValidators := RandValidatorSet(numValidators, votingPower)
 	return NewVoteSet("test_chain_id", height, round, type_, valSet), valSet, privValidators