diff --git a/app/scripts/controllers/transactions.js b/app/scripts/controllers/transactions.js
index 3e3909361..7e2cc15da 100644
--- a/app/scripts/controllers/transactions.js
+++ b/app/scripts/controllers/transactions.js
@@ -250,7 +250,7 @@ module.exports = class TransactionController extends EventEmitter {
       // wait for a nonce
       nonceLock = await this.nonceTracker.getNonceLock(fromAddress)
       // add nonce to txParams
-      // if txMeta has lastGasPrice then it is a retry at same nonce with higher 
+      // if txMeta has lastGasPrice then it is a retry at same nonce with higher
       // gas price transaction and their for the nonce should not be calculated
       const nonce = txMeta.lastGasPrice ? txMeta.txParams.nonce : nonceLock.nextNonce
       txMeta.txParams.nonce = ethUtil.addHexPrefix(nonce.toString(16))
@@ -273,12 +273,14 @@ module.exports = class TransactionController extends EventEmitter {
 
   async signTransaction (txId) {
     const txMeta = this.txStateManager.getTx(txId)
-    const txParams = txMeta.txParams
-    const fromAddress = txParams.from
     // add network/chain id
-    txParams.chainId = ethUtil.addHexPrefix(this.getChainId().toString(16))
+    const chainId = this.getChainId()
+    const txParams = Object.assign({}, txMeta.txParams, { chainId })
+    // sign tx
+    const fromAddress = txParams.from
     const ethTx = new Transaction(txParams)
     await this.signEthTx(ethTx, fromAddress)
+    // set state to signed
     this.txStateManager.setTxStatusSigned(txMeta.id)
     const rawTx = ethUtil.bufferToHex(ethTx.serialize())
     return rawTx
diff --git a/app/scripts/lib/tx-state-manager.js b/app/scripts/lib/tx-state-manager.js
index ab344ae9b..23c915a61 100644
--- a/app/scripts/lib/tx-state-manager.js
+++ b/app/scripts/lib/tx-state-manager.js
@@ -106,12 +106,9 @@ module.exports = class TransactionStateManager extends EventEmitter {
   }
 
   updateTx (txMeta, note) {
+    // validate txParams
     if (txMeta.txParams) {
-      Object.keys(txMeta.txParams).forEach((key) => {
-        const value = txMeta.txParams[key]
-        if (typeof value !== 'string') console.error(`${key}: ${value} in txParams is not a string`)
-        if (!ethUtil.isHexPrefixed(value)) console.error('is not hex prefixed, anything on txParams must be hex prefixed')
-      })
+      this.validateTxParams(txMeta.txParams)
     }
 
     // create txMeta snapshot for history
@@ -139,6 +136,15 @@ module.exports = class TransactionStateManager extends EventEmitter {
     this.updateTx(txMeta, `txStateManager#updateTxParams`)
   }
 
+  // validates txParams members by type
+  validateTxParams(txParams) {
+    Object.keys(txParams).forEach((key) => {
+      const value = txParams[key]
+      if (typeof value !== 'string') throw new Error(`${key}: ${value} in txParams is not a string`)
+      if (!ethUtil.isHexPrefixed(value)) throw new Error('is not hex prefixed, everything on txParams must be hex prefixed')
+    })
+  }
+
 /*
   Takes an object of fields to search for eg:
   let thingsToLookFor = {