diff --git a/chain/messagepool/config.go b/chain/messagepool/config.go
index eaf6ca75b..f8f0ee985 100644
--- a/chain/messagepool/config.go
+++ b/chain/messagepool/config.go
@@ -2,6 +2,7 @@ package messagepool
 
 import (
 	"encoding/json"
+	"fmt"
 	"time"
 
 	"github.com/filecoin-project/lotus/chain/types"
@@ -35,10 +36,6 @@ func loadConfig(ds dtypes.MetadataDS) (*types.MpoolConfig, error) {
 	}
 	cfg := new(types.MpoolConfig)
 	err = json.Unmarshal(cfgBytes, cfg)
-	if cfg.GasLimitOverestimation == 0 {
-		// TODO: remove in next reset
-		cfg.GasLimitOverestimation = GasLimitOverestimation
-	}
 	return cfg, err
 }
 
@@ -56,16 +53,32 @@ func (mp *MessagePool) GetConfig() *types.MpoolConfig {
 	return mp.cfg.Clone()
 }
 
-func (mp *MessagePool) SetConfig(cfg *types.MpoolConfig) {
+func validateConfg(cfg *types.MpoolConfig) error {
+	if cfg.ReplaceByFeeRatio < ReplaceByFeeRatioDefault {
+		return fmt.Errorf("'ReplaceByFeeRatio' is less than required %f < %f",
+			cfg.ReplaceByFeeRatio, ReplaceByFeeRatioDefault)
+	}
+	if cfg.GasLimitOverestimation < 1 {
+		return fmt.Errorf("'GasLimitOverestimation' cannot be less than 1")
+	}
+	return nil
+}
+
+func (mp *MessagePool) SetConfig(cfg *types.MpoolConfig) error {
+	if err := validateConfg(cfg); err != nil {
+		return err
+	}
 	cfg = cfg.Clone()
+
 	mp.cfgLk.Lock()
 	mp.cfg = cfg
-	mp.rbfNum = types.NewInt(uint64((cfg.ReplaceByFeeRatio - 1) * RbfDenom))
 	err := saveConfig(cfg, mp.ds)
 	if err != nil {
 		log.Warnf("error persisting mpool config: %s", err)
 	}
 	mp.cfgLk.Unlock()
+
+	return nil
 }
 
 func DefaultConfig() *types.MpoolConfig {
diff --git a/chain/messagepool/messagepool.go b/chain/messagepool/messagepool.go
index c18f5f5ae..8271dfbb5 100644
--- a/chain/messagepool/messagepool.go
+++ b/chain/messagepool/messagepool.go
@@ -38,6 +38,9 @@ var log = logging.Logger("messagepool")
 
 const futureDebug = false
 
+var rbfNumBig = types.NewInt(uint64((ReplaceByFeeRatioDefault - 1) * RbfDenom))
+var rbfDenomBig = types.NewInt(RbfDenom)
+
 const RbfDenom = 256
 
 var RepublishInterval = pubsub.TimeCacheDuration + time.Duration(5*build.BlockDelaySecs+build.PropagationDelaySecs)*time.Second
@@ -81,8 +84,6 @@ type MessagePool struct {
 	cfgLk sync.Mutex
 	cfg   *types.MpoolConfig
 
-	rbfNum, rbfDenom types.BigInt
-
 	api Provider
 
 	minGasPrice types.BigInt
@@ -126,7 +127,7 @@ func (ms *msgSet) add(m *types.SignedMessage, mp *MessagePool) (bool, error) {
 		if m.Cid() != exms.Cid() {
 			// check if RBF passes
 			minPrice := exms.Message.GasPremium
-			minPrice = types.BigAdd(minPrice, types.BigDiv(types.BigMul(minPrice, mp.rbfNum), mp.rbfDenom))
+			minPrice = types.BigAdd(minPrice, types.BigDiv(types.BigMul(minPrice, rbfNumBig), rbfDenomBig))
 			minPrice = types.BigAdd(minPrice, types.NewInt(1))
 			if types.BigCmp(m.Message.GasPremium, minPrice) >= 0 {
 				log.Infow("add with RBF", "oldpremium", exms.Message.GasPremium,
@@ -172,8 +173,6 @@ func New(api Provider, ds dtypes.MetadataDS, netName dtypes.NetworkName) (*Messa
 		api:           api,
 		netName:       netName,
 		cfg:           cfg,
-		rbfNum:        types.NewInt(uint64((cfg.ReplaceByFeeRatio - 1) * RbfDenom)),
-		rbfDenom:      types.NewInt(RbfDenom),
 	}
 
 	// enable initial prunes
diff --git a/chain/types/message.go b/chain/types/message.go
index b806fa9e4..e9d932ac2 100644
--- a/chain/types/message.go
+++ b/chain/types/message.go
@@ -170,6 +170,10 @@ func (m *Message) ValidForBlockInclusion(minGas int64) error {
 		return xerrors.New("'GasPremium' field cannot be negative")
 	}
 
+	if m.GasPremium.GreaterThan(m.GasFeeCap) {
+		return xerrors.New("'GasFeeCap' less than 'GasPremium'")
+	}
+
 	if m.GasLimit > build.BlockGasLimit {
 		return xerrors.New("'GasLimit' field cannot be greater than a block's gas limit")
 	}
diff --git a/node/impl/full/mpool.go b/node/impl/full/mpool.go
index cd6adef6d..407824eea 100644
--- a/node/impl/full/mpool.go
+++ b/node/impl/full/mpool.go
@@ -13,6 +13,7 @@ import (
 	"github.com/filecoin-project/lotus/chain/store"
 	"github.com/filecoin-project/lotus/chain/types"
 	"github.com/filecoin-project/lotus/node/modules/dtypes"
+	"github.com/filecoin-project/specs-actors/actors/abi/big"
 )
 
 type MpoolAPI struct {
@@ -33,8 +34,7 @@ func (a *MpoolAPI) MpoolGetConfig(context.Context) (*types.MpoolConfig, error) {
 }
 
 func (a *MpoolAPI) MpoolSetConfig(ctx context.Context, cfg *types.MpoolConfig) error {
-	a.Mpool.SetConfig(cfg)
-	return nil
+	return a.Mpool.SetConfig(cfg)
 }
 
 func (a *MpoolAPI) MpoolSelect(ctx context.Context, tsk types.TipSetKey, ticketQuality float64) ([]*types.SignedMessage, error) {
@@ -145,7 +145,7 @@ func (a *MpoolAPI) MpoolPushMessage(ctx context.Context, msg *types.Message) (*t
 		if err != nil {
 			return nil, xerrors.Errorf("estimating fee cap: %w", err)
 		}
-		msg.GasFeeCap = feeCap
+		msg.GasFeeCap = big.Add(feeCap, msg.GasPremium)
 	}
 
 	return a.Mpool.PushWithNonce(ctx, msg.From, func(from address.Address, nonce uint64) (*types.SignedMessage, error) {