diff --git a/types/tx.go b/types/tx.go
index 811ab1fd..19274e95 100644
--- a/types/tx.go
+++ b/types/tx.go
@@ -1,6 +1,7 @@
 package types
 
 import (
+	"encoding/json"
 	"errors"
 	"io"
 
@@ -135,7 +136,7 @@ type SendTx struct {
 }
 
 func (tx *SendTx) WriteSignBytes(chainID string, w io.Writer, n *int64, err *error) {
-	binary.WriteTo([]byte(Fmt(`{"chain_id":"%s"`, chainID)), w, n, err)
+	binary.WriteTo([]byte(Fmt(`{"chain_id":%s`, jsonEscape(chainID))), w, n, err)
 	binary.WriteTo([]byte(Fmt(`,"tx":[%v,{"inputs":[`, TxTypeSend)), w, n, err)
 	for i, in := range tx.Inputs {
 		in.WriteSignBytes(w, n, err)
@@ -168,7 +169,7 @@ type CallTx struct {
 }
 
 func (tx *CallTx) WriteSignBytes(chainID string, w io.Writer, n *int64, err *error) {
-	binary.WriteTo([]byte(Fmt(`{"chain_id":"%s"`, chainID)), w, n, err)
+	binary.WriteTo([]byte(Fmt(`{"chain_id":%s`, jsonEscape(chainID))), w, n, err)
 	binary.WriteTo([]byte(Fmt(`,"tx":[%v,{"address":"%X","data":"%X"`, TxTypeCall, tx.Address, tx.Data)), w, n, err)
 	binary.WriteTo([]byte(Fmt(`,"fee":%v,"gas_limit":%v,"input":`, tx.Fee, tx.GasLimit)), w, n, err)
 	tx.Input.WriteSignBytes(w, n, err)
@@ -189,10 +190,11 @@ type NameTx struct {
 }
 
 func (tx *NameTx) WriteSignBytes(chainID string, w io.Writer, n *int64, err *error) {
-	binary.WriteTo([]byte(Fmt(`{"chain_id":"%s"`, chainID)), w, n, err)
-	binary.WriteTo([]byte(Fmt(`,"tx":[%v,{"name":"%s","data":"%s"`, TxTypeName, tx.Name, tx.Data)), w, n, err)
-	binary.WriteTo([]byte(Fmt(`,"fee":%v,"input":`, tx.Fee)), w, n, err)
+	binary.WriteTo([]byte(Fmt(`{"chain_id":%s`, jsonEscape(chainID))), w, n, err)
+	binary.WriteTo([]byte(Fmt(`,"tx":[%v,{"data":%s,"fee":%v`, TxTypeName, jsonEscape(tx.Data), tx.Fee)), w, n, err)
+	binary.WriteTo([]byte(Fmt(`,"input":`, tx.Input)), w, n, err)
 	tx.Input.WriteSignBytes(w, n, err)
+	binary.WriteTo([]byte(Fmt(`,"name":%s`, jsonEscape(tx.Name))), w, n, err)
 	binary.WriteTo([]byte(`}]}`), w, n, err)
 }
 
@@ -236,7 +238,7 @@ type BondTx struct {
 }
 
 func (tx *BondTx) WriteSignBytes(chainID string, w io.Writer, n *int64, err *error) {
-	binary.WriteTo([]byte(Fmt(`{"chain_id":"%s"`, chainID)), w, n, err)
+	binary.WriteTo([]byte(Fmt(`{"chain_id":%s`, jsonEscape(chainID))), w, n, err)
 	binary.WriteTo([]byte(Fmt(`,"tx":[%v,{"inputs":[`, TxTypeBond)), w, n, err)
 	for i, in := range tx.Inputs {
 		in.WriteSignBytes(w, n, err)
@@ -269,7 +271,7 @@ type UnbondTx struct {
 }
 
 func (tx *UnbondTx) WriteSignBytes(chainID string, w io.Writer, n *int64, err *error) {
-	binary.WriteTo([]byte(Fmt(`{"chain_id":"%s"`, chainID)), w, n, err)
+	binary.WriteTo([]byte(Fmt(`{"chain_id":%s`, jsonEscape(chainID))), w, n, err)
 	binary.WriteTo([]byte(Fmt(`,"tx":[%v,{"address":"%X","height":%v}]}`, TxTypeUnbond, tx.Address, tx.Height)), w, n, err)
 }
 
@@ -286,7 +288,7 @@ type RebondTx struct {
 }
 
 func (tx *RebondTx) WriteSignBytes(chainID string, w io.Writer, n *int64, err *error) {
-	binary.WriteTo([]byte(Fmt(`{"chain_id":"%s"`, chainID)), w, n, err)
+	binary.WriteTo([]byte(Fmt(`{"chain_id":%s`, jsonEscape(chainID))), w, n, err)
 	binary.WriteTo([]byte(Fmt(`,"tx":[%v,{"address":"%X","height":%v}]}`, TxTypeRebond, tx.Address, tx.Height)), w, n, err)
 }
 
@@ -316,3 +318,14 @@ func TxId(chainID string, tx Tx) []byte {
 	signBytes := account.SignBytes(chainID, tx)
 	return binary.BinaryRipemd160(signBytes)
 }
+
+//--------------------------------------------------------------------------------
+
+// Contract: This function is deterministic and completely reversible.
+func jsonEscape(str string) string {
+	escapedBytes, err := json.Marshal(str)
+	if err != nil {
+		panic(Fmt("Error json-escaping a string", str))
+	}
+	return string(escapedBytes)
+}