diff --git a/chain/deals/client.go b/chain/deals/client.go
index 9346f2905..946e6cb93 100644
--- a/chain/deals/client.go
+++ b/chain/deals/client.go
@@ -74,6 +74,11 @@ type clientDealUpdate struct {
 	mut      func(*ClientDeal)
 }
 
+type clientApi struct {
+	full.ChainAPI
+	full.StateAPI
+}
+
 func NewClient(sm *stmgr.StateManager, chain *store.ChainStore, h host.Host, w *wallet.Wallet, dag dtypes.ClientDAG, dataTransfer dtypes.ClientDataTransfer, discovery *discovery.Local, fm *market.FundMgr, deals dtypes.ClientDealStore, chainapi full.ChainAPI, stateapi full.StateAPI) *Client {
 	c := &Client{
 		sm:           sm,
@@ -84,7 +89,7 @@ func NewClient(sm *stmgr.StateManager, chain *store.ChainStore, h host.Host, w *
 		dag:          dag,
 		discovery:    discovery,
 		fm:           fm,
-		events:       events.NewEvents(context.TODO(), &struct {full.ChainAPI; full.StateAPI}{chainapi, stateapi}),
+		events:       events.NewEvents(context.TODO(), &clientApi{chainapi, stateapi}),
 
 		deals: deals,
 		conns: map[cid.Cid]inet.Stream{},
diff --git a/chain/events/utils.go b/chain/events/utils.go
index 3dd34a1db..13d620da8 100644
--- a/chain/events/utils.go
+++ b/chain/events/utils.go
@@ -3,6 +3,8 @@ package events
 import (
 	"context"
 
+	"golang.org/x/xerrors"
+
 	"github.com/filecoin-project/lotus/chain/types"
 )
 
@@ -30,6 +32,10 @@ func (e *calledEvents) CheckMsg(ctx context.Context, msg *types.Message, hnd Cal
 
 func(e *calledEvents) MatchMsg(inmsg *types.Message) MatchFunc {
 	return func(msg *types.Message) (bool, error) {
+		if msg.From == inmsg.From && msg.Nonce == inmsg.Nonce && !inmsg.Equals(msg) {
+			return false, xerrors.Errorf("matching msg %s from %s, nonce %d: got duplicate origin/nonce msg %s", inmsg.Cid(), inmsg.From, inmsg.Nonce, msg.Nonce)
+		}
+
 		return inmsg.Equals(msg), nil
 	}
 }
diff --git a/storage/miner.go b/storage/miner.go
index c2ebb0570..fe0839467 100644
--- a/storage/miner.go
+++ b/storage/miner.go
@@ -55,7 +55,7 @@ type storageMinerApi interface {
 	StateMinerSectors(context.Context, address.Address, *types.TipSet) ([]*api.ChainSectorInfo, error)
 	StateMinerProvingSet(context.Context, address.Address, *types.TipSet) ([]*api.ChainSectorInfo, error)
 	StateMinerSectorSize(context.Context, address.Address, *types.TipSet) (uint64, error)
-	StateWaitMsg(context.Context, cid.Cid) (*api.MsgWait, error)  // TODO: removeme
+	StateWaitMsg(context.Context, cid.Cid) (*api.MsgWait, error)  // TODO: removeme eventually
 	StateGetActor(ctx context.Context, actor address.Address, ts *types.TipSet) (*types.Actor, error)
 	StateGetReceipt(context.Context, cid.Cid, *types.TipSet) (*types.MessageReceipt, error)