diff --git a/consensus/engine/consensus_engine.go b/consensus/engine/consensus_engine.go
index 90ef3316b..a032c5123 100644
--- a/consensus/engine/consensus_engine.go
+++ b/consensus/engine/consensus_engine.go
@@ -45,6 +45,9 @@ type ChainReader interface {
 	// ReadActiveValidatorList retrieves the list of active validators
 	ReadActiveValidatorList() ([]common.Address, error)
 
+	// ReadValidatorList retrieves the list of all validators
+	ReadValidatorList() ([]common.Address, error)
+
 	// Methods needed for EPoS committee assignment calculation
 	committee.StakingCandidatesReader
 
diff --git a/core/state_transition.go b/core/state_transition.go
index b63cd10aa..314d51002 100644
--- a/core/state_transition.go
+++ b/core/state_transition.go
@@ -41,6 +41,7 @@ var (
 	errCommissionRateChangeTooFast = errors.New("commission rate can not be changed more than MaxChangeRate within the same epoch")
 	errCommissionRateChangeTooHigh = errors.New("commission rate can not be higher than MaxCommissionRate")
 	errNoRewardsToCollect          = errors.New("no rewards to collect")
+	errNegativeAmount              = errors.New("amount can not be negative")
 )
 
 /*
@@ -367,6 +368,10 @@ func (st *StateTransition) StakingTransitionDb() (usedGas uint64, err error) {
 }
 
 func (st *StateTransition) applyCreateValidatorTx(createValidator *staking.CreateValidator, blockNum *big.Int) error {
+	if createValidator.Amount.Sign() == -1 {
+		return errNegativeAmount
+	}
+
 	if st.state.IsValidator(createValidator.ValidatorAddress) {
 		return errValidatorExist
 	}
@@ -429,6 +434,10 @@ func (st *StateTransition) applyEditValidatorTx(editValidator *staking.EditValid
 }
 
 func (st *StateTransition) applyDelegateTx(delegate *staking.Delegate) error {
+	if delegate.Amount.Sign() == -1 {
+		return errNegativeAmount
+	}
+
 	if !st.state.IsValidator(delegate.ValidatorAddress) {
 		return errValidatorNotExist
 	}
@@ -465,7 +474,7 @@ func (st *StateTransition) applyDelegateTx(delegate *staking.Delegate) error {
 
 				// Secondly, if all locked token are used, try use the balance.
 				if err == nil && undelegateAmount.Cmp(big.NewInt(0)) > 0 {
-					stateDB.SubBalance(delegate.DelegatorAddress, delegate.Amount)
+					stateDB.SubBalance(delegate.DelegatorAddress, undelegateAmount)
 				}
 				return err
 			}
@@ -490,6 +499,10 @@ func (st *StateTransition) applyDelegateTx(delegate *staking.Delegate) error {
 }
 
 func (st *StateTransition) applyUndelegateTx(undelegate *staking.Undelegate) error {
+	if undelegate.Amount.Sign() == -1 {
+		return errNegativeAmount
+	}
+
 	if !st.state.IsValidator(undelegate.ValidatorAddress) {
 		return errValidatorNotExist
 	}
diff --git a/internal/chain/engine.go b/internal/chain/engine.go
index 31b637058..a3ccca832 100644
--- a/internal/chain/engine.go
+++ b/internal/chain/engine.go
@@ -203,12 +203,10 @@ func (e *engineImpl) Finalize(
 		return nil, nil, ctxerror.New("cannot pay block reward").WithCause(err)
 	}
 
-	// TODO Shouldnt this logic only apply to beaconchain, right?
 	// Withdraw unlocked tokens to the delegators' accounts
 	// Only do such at the last block of an epoch
 	if header.ShardID() == shard.BeaconChainShardID && len(header.ShardState()) > 0 {
-		// TODO: make sure we are using the correct validator list
-		validators, err := chain.ReadActiveValidatorList()
+		validators, err := chain.ReadValidatorList()
 		if err != nil {
 			return nil, nil, ctxerror.New("failed to read active validators").WithCause(err)
 		}