diff --git a/CHANGELOG_PENDING.md b/CHANGELOG_PENDING.md
index a3c8c747..c57b6b82 100644
--- a/CHANGELOG_PENDING.md
+++ b/CHANGELOG_PENDING.md
@@ -24,6 +24,9 @@ program](https://hackerone.com/tendermint).
 - [rpc] \#2252 Add `/broadcast_evidence` endpoint to submit double signing and other types of evidence
 - [rpc] \#3818 Make `max_body_bytes` and `max_header_bytes` configurable
 - [p2p] \#3664 p2p/conn: reuse buffer when write/read from secret connection
+- [mempool] \#3826 Make `max_msg_bytes` configurable
 - [blockchain] \#3561 Add early version of the new blockchain reactor, which is supposed to be more modular and testable compared to the old version. To try it, you'll have to change `version` in the config file, [here](https://github.com/tendermint/tendermint/blob/master/config/toml.go#L303) NOTE: It's not ready for a production yet. For further information, see [ADR-40](https://github.com/tendermint/tendermint/blob/master/docs/architecture/adr-040-blockchain-reactor-refactor.md) & [ADR-43](https://github.com/tendermint/tendermint/blob/master/docs/architecture/adr-043-blockchain-riri-org.md)
 
 ### BUG FIXES:
+
+- [rpc] \#3813 Return err if page is incorrect (less than 0 or greater than total pages)
diff --git a/config/config.go b/config/config.go
index cefe6ba6..b00702ce 100644
--- a/config/config.go
+++ b/config/config.go
@@ -637,6 +637,7 @@ type MempoolConfig struct {
 	Size        int    `mapstructure:"size"`
 	MaxTxsBytes int64  `mapstructure:"max_txs_bytes"`
 	CacheSize   int    `mapstructure:"cache_size"`
+	MaxMsgBytes int    `mapstructure:"max_msg_bytes"`
 }
 
 // DefaultMempoolConfig returns a default configuration for the Tendermint mempool
@@ -650,6 +651,7 @@ func DefaultMempoolConfig() *MempoolConfig {
 		Size:        5000,
 		MaxTxsBytes: 1024 * 1024 * 1024, // 1GB
 		CacheSize:   10000,
+		MaxMsgBytes: 1024 * 1024, // 1MB
 	}
 }
 
@@ -682,6 +684,9 @@ func (cfg *MempoolConfig) ValidateBasic() error {
 	if cfg.CacheSize < 0 {
 		return errors.New("cache_size can't be negative")
 	}
+	if cfg.MaxMsgBytes < 0 {
+		return errors.New("max_msg_bytes can't be negative")
+	}
 	return nil
 }
 
diff --git a/config/toml.go b/config/toml.go
index 6847342e..5679a1ca 100644
--- a/config/toml.go
+++ b/config/toml.go
@@ -302,6 +302,9 @@ cache_size = {{ .Mempool.CacheSize }}
 #   2) "v1" - refactor of v0 version for better testability
 version = "{{ .FastSync.Version }}"
 
+# Limit the size of TxMessage
+max_msg_bytes = {{ .Mempool.MaxMsgBytes }}
+
 ##### consensus configuration options #####
 [consensus]
 
diff --git a/docs/tendermint-core/configuration.md b/docs/tendermint-core/configuration.md
index eea67766..20495814 100644
--- a/docs/tendermint-core/configuration.md
+++ b/docs/tendermint-core/configuration.md
@@ -248,6 +248,9 @@ cache_size = 10000
 #   2) "v1" - refactor of v0 version for better testability
 version = "v0"
 
+# Limit the size of TxMessage
+max_msg_bytes = 1048576
+
 ##### consensus configuration options #####
 [consensus]
 
diff --git a/mempool/clist_mempool.go b/mempool/clist_mempool.go
index 4042e9b4..81123cb6 100644
--- a/mempool/clist_mempool.go
+++ b/mempool/clist_mempool.go
@@ -220,9 +220,10 @@ func (mem *CListMempool) CheckTxWithInfo(tx types.Tx, cb func(*abci.Response), t
 	var (
 		memSize  = mem.Size()
 		txsBytes = mem.TxsBytes()
+		txSize   = len(tx)
 	)
 	if memSize >= mem.config.Size ||
-		int64(len(tx))+txsBytes > mem.config.MaxTxsBytes {
+		int64(txSize)+txsBytes > mem.config.MaxTxsBytes {
 		return ErrMempoolIsFull{
 			memSize, mem.config.Size,
 			txsBytes, mem.config.MaxTxsBytes}
@@ -231,8 +232,8 @@ func (mem *CListMempool) CheckTxWithInfo(tx types.Tx, cb func(*abci.Response), t
 	// The size of the corresponding amino-encoded TxMessage
 	// can't be larger than the maxMsgSize, otherwise we can't
 	// relay it to peers.
-	if len(tx) > maxTxSize {
-		return ErrTxTooLarge
+	if max := calcMaxTxSize(mem.config.MaxMsgBytes); txSize > max {
+		return ErrTxTooLarge{max, txSize}
 	}
 
 	if mem.preCheck != nil {
diff --git a/mempool/clist_mempool_test.go b/mempool/clist_mempool_test.go
index 90d0ed1a..e2ebca92 100644
--- a/mempool/clist_mempool_test.go
+++ b/mempool/clist_mempool_test.go
@@ -426,6 +426,9 @@ func TestMempoolMaxMsgSize(t *testing.T) {
 	mempl, cleanup := newMempoolWithApp(cc)
 	defer cleanup()
 
+	maxMsgSize := mempl.config.MaxMsgBytes
+	maxTxSize := calcMaxTxSize(mempl.config.MaxMsgBytes)
+
 	testCases := []struct {
 		len int
 		err bool
@@ -462,7 +465,7 @@ func TestMempoolMaxMsgSize(t *testing.T) {
 			require.NoError(t, err, caseString)
 		} else {
 			require.True(t, len(encoded) > maxMsgSize, caseString)
-			require.Equal(t, err, ErrTxTooLarge, caseString)
+			require.Equal(t, err, ErrTxTooLarge{maxTxSize, testCase.len}, caseString)
 		}
 	}
 
diff --git a/mempool/errors.go b/mempool/errors.go
index ac2a9b3c..c5140bdf 100644
--- a/mempool/errors.go
+++ b/mempool/errors.go
@@ -9,11 +9,18 @@ import (
 var (
 	// ErrTxInCache is returned to the client if we saw tx earlier
 	ErrTxInCache = errors.New("Tx already exists in cache")
-
-	// ErrTxTooLarge means the tx is too big to be sent in a message to other peers
-	ErrTxTooLarge = fmt.Errorf("Tx too large. Max size is %d", maxTxSize)
 )
 
+// ErrTxTooLarge means the tx is too big to be sent in a message to other peers
+type ErrTxTooLarge struct {
+	max    int
+	actual int
+}
+
+func (e ErrTxTooLarge) Error() string {
+	return fmt.Sprintf("Tx too large. Max size is %d, but got %d", e.max, e.actual)
+}
+
 // ErrMempoolIsFull means Tendermint & an application can't handle that much load
 type ErrMempoolIsFull struct {
 	numTxs int
diff --git a/mempool/reactor.go b/mempool/reactor.go
index 65ccd7df..0ca27340 100644
--- a/mempool/reactor.go
+++ b/mempool/reactor.go
@@ -19,8 +19,7 @@ import (
 const (
 	MempoolChannel = byte(0x30)
 
-	maxMsgSize = 1048576        // 1MB TODO make it configurable
-	maxTxSize  = maxMsgSize - 8 // account for amino overhead of TxMessage
+	aminoOverheadForTxMessage = 8
 
 	peerCatchupSleepIntervalMS = 100 // If peer is behind, sleep this amount
 
@@ -156,7 +155,7 @@ func (memR *Reactor) RemovePeer(peer p2p.Peer, reason interface{}) {
 // Receive implements Reactor.
 // It adds any received transactions to the mempool.
 func (memR *Reactor) Receive(chID byte, src p2p.Peer, msgBytes []byte) {
-	msg, err := decodeMsg(msgBytes)
+	msg, err := memR.decodeMsg(msgBytes)
 	if err != nil {
 		memR.Logger.Error("Error decoding message", "src", src, "chId", chID, "msg", msg, "err", err, "bytes", msgBytes)
 		memR.Switch.StopPeerForError(src, err)
@@ -263,9 +262,9 @@ func RegisterMempoolMessages(cdc *amino.Codec) {
 	cdc.RegisterConcrete(&TxMessage{}, "tendermint/mempool/TxMessage", nil)
 }
 
-func decodeMsg(bz []byte) (msg MempoolMessage, err error) {
-	if len(bz) > maxMsgSize {
-		return msg, fmt.Errorf("Msg exceeds max size (%d > %d)", len(bz), maxMsgSize)
+func (memR *Reactor) decodeMsg(bz []byte) (msg MempoolMessage, err error) {
+	if l := len(bz); l > memR.config.MaxMsgBytes {
+		return msg, ErrTxTooLarge{memR.config.MaxMsgBytes, l}
 	}
 	err = cdc.UnmarshalBinaryBare(bz, &msg)
 	return
@@ -282,3 +281,9 @@ type TxMessage struct {
 func (m *TxMessage) String() string {
 	return fmt.Sprintf("[TxMessage %v]", m.Tx)
 }
+
+// calcMaxTxSize returns the max size of Tx
+// account for amino overhead of TxMessage
+func calcMaxTxSize(maxMsgSize int) int {
+	return maxMsgSize - aminoOverheadForTxMessage
+}
diff --git a/rpc/core/pipe.go b/rpc/core/pipe.go
index a0fc7b9b..9581b89d 100644
--- a/rpc/core/pipe.go
+++ b/rpc/core/pipe.go
@@ -1,6 +1,7 @@
 package core
 
 import (
+	"fmt"
 	"time"
 
 	cfg "github.com/tendermint/tendermint/config"
@@ -145,19 +146,24 @@ func SetConfig(c cfg.RPCConfig) {
 	config = c
 }
 
-func validatePage(page, perPage, totalCount int) int {
+func validatePage(page, perPage, totalCount int) (int, error) {
 	if perPage < 1 {
-		return 1
+		panic(fmt.Sprintf("zero or negative perPage: %d", perPage))
+	}
+
+	if page == 0 {
+		return 1, nil // default
 	}
 
 	pages := ((totalCount - 1) / perPage) + 1
-	if page < 1 {
-		page = 1
-	} else if page > pages {
-		page = pages
+	if pages == 0 {
+		pages = 1 // one page (even if it's empty)
+	}
+	if page < 0 || page > pages {
+		return 1, fmt.Errorf("page should be within [0, %d] range, given %d", pages, page)
 	}
 
-	return page
+	return page, nil
 }
 
 func validatePerPage(perPage int) int {
diff --git a/rpc/core/pipe_test.go b/rpc/core/pipe_test.go
index 19ed11fc..93aff3e5 100644
--- a/rpc/core/pipe_test.go
+++ b/rpc/core/pipe_test.go
@@ -14,33 +14,39 @@ func TestPaginationPage(t *testing.T) {
 		perPage    int
 		page       int
 		newPage    int
+		expErr     bool
 	}{
-		{0, 0, 1, 1},
+		{0, 10, 1, 1, false},
 
-		{0, 10, 0, 1},
-		{0, 10, 1, 1},
-		{0, 10, 2, 1},
+		{0, 10, 0, 1, false},
+		{0, 10, 1, 1, false},
+		{0, 10, 2, 0, true},
 
-		{5, 10, -1, 1},
-		{5, 10, 0, 1},
-		{5, 10, 1, 1},
-		{5, 10, 2, 1},
-		{5, 10, 2, 1},
+		{5, 10, -1, 0, true},
+		{5, 10, 0, 1, false},
+		{5, 10, 1, 1, false},
+		{5, 10, 2, 0, true},
+		{5, 10, 2, 0, true},
 
-		{5, 5, 1, 1},
-		{5, 5, 2, 1},
-		{5, 5, 3, 1},
+		{5, 5, 1, 1, false},
+		{5, 5, 2, 0, true},
+		{5, 5, 3, 0, true},
 
-		{5, 3, 2, 2},
-		{5, 3, 3, 2},
+		{5, 3, 2, 2, false},
+		{5, 3, 3, 0, true},
 
-		{5, 2, 2, 2},
-		{5, 2, 3, 3},
-		{5, 2, 4, 3},
+		{5, 2, 2, 2, false},
+		{5, 2, 3, 3, false},
+		{5, 2, 4, 0, true},
 	}
 
 	for _, c := range cases {
-		p := validatePage(c.page, c.perPage, c.totalCount)
+		p, err := validatePage(c.page, c.perPage, c.totalCount)
+		if c.expErr {
+			assert.Error(t, err)
+			continue
+		}
+
 		assert.Equal(t, c.newPage, p, fmt.Sprintf("%v", c))
 	}
 
diff --git a/rpc/core/tx.go b/rpc/core/tx.go
index 575553f8..dba457c3 100644
--- a/rpc/core/tx.go
+++ b/rpc/core/tx.go
@@ -202,7 +202,10 @@ func TxSearch(ctx *rpctypes.Context, query string, prove bool, page, perPage int
 
 	totalCount := len(results)
 	perPage = validatePerPage(perPage)
-	page = validatePage(page, perPage, totalCount)
+	page, err = validatePage(page, perPage, totalCount)
+	if err != nil {
+		return nil, err
+	}
 	skipCount := validateSkipCount(page, perPage)
 
 	apiResults := make([]*ctypes.ResultTx, cmn.MinInt(perPage, totalCount-skipCount))