diff --git a/chain/messagepool/selection.go b/chain/messagepool/selection.go
index 7446ee4e4b4..d7f7750fc6d 100644
--- a/chain/messagepool/selection.go
+++ b/chain/messagepool/selection.go
@@ -63,6 +63,10 @@ func (mp *MessagePool) SelectMessages(ctx context.Context, ts *types.TipSet, tq
 		return nil, err
 	}
 
+	if sm == nil {
+		return nil, nil
+	}
+
 	// one last sanity check
 	if len(sm.msgs) > build.BlockMessageLimit {
 		sm.msgs = sm.msgs[:build.BlockMessageLimit]
diff --git a/chain/messagepool/selection_test.go b/chain/messagepool/selection_test.go
index 72739b6a14a..f3389896f6d 100644
--- a/chain/messagepool/selection_test.go
+++ b/chain/messagepool/selection_test.go
@@ -13,6 +13,10 @@ import (
 	"sort"
 	"testing"
 
+	"github.com/filecoin-project/go-state-types/crypto"
+
+	cbg "github.com/whyrusleeping/cbor-gen"
+
 	"github.com/filecoin-project/go-address"
 	"github.com/ipfs/go-cid"
 	"github.com/ipfs/go-datastore"
@@ -527,7 +531,7 @@ func TestBasicMessageSelection(t *testing.T) {
 	}
 }
 
-func TestMessageSelectionTrimming(t *testing.T) {
+func TestMessageSelectionTrimmingGas(t *testing.T) {
 	mp, tma := makeTestMpool()
 
 	// the actors
@@ -590,6 +594,199 @@ func TestMessageSelectionTrimming(t *testing.T) {
 
 }
 
+func TestMessageSelectionTrimmingMsgsBasic(t *testing.T) {
+	mp, tma := makeTestMpool()
+
+	// the actors
+	w1, err := wallet.NewWallet(wallet.NewMemKeyStore())
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	a1, err := w1.WalletNew(context.Background(), types.KTSecp256k1)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	block := tma.nextBlock()
+	ts := mock.TipSet(block)
+	tma.applyBlock(t, block)
+
+	tma.setBalance(a1, 1) // in FIL
+
+	// create a larger than selectable chain
+	for i := 0; i < build.BlockMessageLimit; i++ {
+		m := makeTestMessage(w1, a1, a1, uint64(i), 300000, 100)
+		mustAdd(t, mp, m)
+	}
+
+	msgs, err := mp.SelectMessages(context.Background(), ts, 1.0)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	expected := cbg.MaxLength
+	if len(msgs) != expected {
+		t.Fatalf("expected %d messages, but got %d", expected, len(msgs))
+	}
+
+	mGasLimit := int64(0)
+	for _, m := range msgs {
+		mGasLimit += m.Message.GasLimit
+	}
+	if mGasLimit > build.BlockGasLimit {
+		t.Fatal("selected messages gas limit exceeds block gas limit!")
+	}
+
+}
+
+func TestMessageSelectionTrimmingMsgsTwoSendersBasic(t *testing.T) {
+	mp, tma := makeTestMpool()
+
+	// the actors
+	w1, err := wallet.NewWallet(wallet.NewMemKeyStore())
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	a1, err := w1.WalletNew(context.Background(), types.KTSecp256k1)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	w2, err := wallet.NewWallet(wallet.NewMemKeyStore())
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	a2, err := w2.WalletNew(context.Background(), types.KTBLS)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	block := tma.nextBlock()
+	ts := mock.TipSet(block)
+	tma.applyBlock(t, block)
+
+	tma.setBalance(a1, 1) // in FIL
+	tma.setBalance(a2, 1) // in FIL
+
+	// create 2 larger than selectable chains
+	for i := 0; i < build.BlockMessageLimit; i++ {
+		m := makeTestMessage(w1, a1, a2, uint64(i), 300000, 100)
+		mustAdd(t, mp, m)
+		// a2's messages are preferred
+		m = makeTestMessage(w2, a2, a1, uint64(i), 300000, 1000)
+		mustAdd(t, mp, m)
+	}
+
+	msgs, err := mp.SelectMessages(context.Background(), ts, 1.0)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	mGasLimit := int64(0)
+	counts := make(map[crypto.SigType]uint)
+	for _, m := range msgs {
+		mGasLimit += m.Message.GasLimit
+		counts[m.Signature.Type]++
+	}
+
+	if mGasLimit > build.BlockGasLimit {
+		t.Fatal("selected messages gas limit exceeds block gas limit!")
+	}
+
+	expected := build.BlockMessageLimit
+	if len(msgs) != expected {
+		t.Fatalf("expected %d messages, but got %d", expected, len(msgs))
+	}
+
+	if counts[crypto.SigTypeBLS] != cbg.MaxLength {
+		t.Fatalf("expected %d bls messages, but got %d", cbg.MaxLength, len(msgs))
+	}
+}
+
+func TestMessageSelectionTrimmingMsgsTwoSendersAdvanced(t *testing.T) {
+	mp, tma := makeTestMpool()
+
+	// the actors
+	w1, err := wallet.NewWallet(wallet.NewMemKeyStore())
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	a1, err := w1.WalletNew(context.Background(), types.KTSecp256k1)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	w2, err := wallet.NewWallet(wallet.NewMemKeyStore())
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	a2, err := w2.WalletNew(context.Background(), types.KTBLS)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	block := tma.nextBlock()
+	ts := mock.TipSet(block)
+	tma.applyBlock(t, block)
+
+	tma.setBalance(a1, 1) // in FIL
+	tma.setBalance(a2, 1) // in FIL
+
+	// create 2 almost max-length chains of equal value
+	i := 0
+	for i = 0; i < cbg.MaxLength-1; i++ {
+		m := makeTestMessage(w1, a1, a2, uint64(i), 300000, 100)
+		mustAdd(t, mp, m)
+		// a2's messages are preferred
+		m = makeTestMessage(w2, a2, a1, uint64(i), 300000, 100)
+		mustAdd(t, mp, m)
+	}
+
+	// a1's 8192th message is worth more than a2's
+	m := makeTestMessage(w1, a1, a2, uint64(i), 300000, 1000)
+	mustAdd(t, mp, m)
+
+	m = makeTestMessage(w2, a2, a1, uint64(i), 300000, 100)
+	mustAdd(t, mp, m)
+
+	i++
+
+	// a2's (unselectable) 8193rd message is worth SO MUCH
+	m = makeTestMessage(w2, a2, a1, uint64(i), 300000, 1000000)
+	mustAdd(t, mp, m)
+
+	msgs, err := mp.SelectMessages(context.Background(), ts, 1.0)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	mGasLimit := int64(0)
+	counts := make(map[crypto.SigType]uint)
+	for _, m := range msgs {
+		mGasLimit += m.Message.GasLimit
+		counts[m.Signature.Type]++
+	}
+
+	if mGasLimit > build.BlockGasLimit {
+		t.Fatal("selected messages gas limit exceeds block gas limit!")
+	}
+
+	expected := build.BlockMessageLimit
+	if len(msgs) != expected {
+		t.Fatalf("expected %d messages, but got %d", expected, len(msgs))
+	}
+
+	// we should have taken the secp chain
+	if counts[crypto.SigTypeSecp256k1] != cbg.MaxLength {
+		t.Fatalf("expected %d bls messages, but got %d", cbg.MaxLength, len(msgs))
+	}
+}
+
 func TestPriorityMessageSelection(t *testing.T) {
 	mp, tma := makeTestMpool()