diff --git a/dev/double-spend-scenario.js b/dev/double-spend-scenario.js
new file mode 100644
index 00000000..73e112c3
--- /dev/null
+++ b/dev/double-spend-scenario.js
@@ -0,0 +1,52 @@
+var db = require('../lib/postgresql_interface')
+var connectionString = 'postgres://lamassu:lamassu@localhost/lamassu'
+db.init(connectionString)
+
+var session = {
+  id: '6ede611c-cd03-11e5-88ee-2b5fcfdb0bc2',
+  fingerprint: 'xx:xx'
+}
+var tx = {
+  fiat: 40,
+  satoshis: 6980000,
+  toAddress: '1xxx',
+  currencyCode: 'CAD',
+  incoming: false
+}
+
+var tx2 = {
+  fiat: 0,
+  satoshis: 6980000,
+  toAddress: '1xxx',
+  currencyCode: 'CAD',
+  incoming: false
+}
+
+db.addOutgoingTx(session, tx, function (err, res) {
+  console.log('DEBUG1')
+  console.log(err)
+  console.log(res)
+})
+
+setTimeout(function () {
+  db.addOutgoingTx(session, tx2, function (err, res) {
+    console.log('DEBUG2')
+    console.log(err)
+    console.log(res)
+  })
+}, 1000)
+
+var bills = {
+  uuid: 'c630338c-cd03-11e5-a9df-dbc9be2e9fbb',
+  currency: 'CAD',
+  toAddress: '1xxx',
+  deviceTime: Date.now(),
+  satoshis: 6980000,
+  fiat: 40
+}
+
+/*
+db.recordBill(session, bills, function (err) {
+  console.log(err)
+})
+*/
diff --git a/lib/plugins.js b/lib/plugins.js
index 0867c43c..a6519956 100644
--- a/lib/plugins.js
+++ b/lib/plugins.js
@@ -121,7 +121,7 @@ function loadOrConfigPlugin(pluginHandle, pluginType, currency,
       pluginHandle = loadPlugin(currentName, pluginConfig);
       currentlyUsedPlugins[pluginType] = currentName
       logger.debug('plugin(%s) loaded: %s', pluginType, pluginHandle.NAME ||
-        currentName);        
+        currentName);
     }
   }
 
@@ -311,6 +311,8 @@ exports.trade = function trade(session, rawTrade, cb) {
     currencyCode: rawTrade.currency
   };
 
+  console.log('****************** DEBUG2 *****************')
+  console.log(db.addOutgoingPending)
   async.parallel([
     async.apply(db.addOutgoingPending, session, tx.currencyCode, tx.toAddress),
     async.apply(db.recordBill, session, rawTrade)
diff --git a/lib/postgresql_interface.js b/lib/postgresql_interface.js
index e969f3d8..86935f2b 100644
--- a/lib/postgresql_interface.js
+++ b/lib/postgresql_interface.js
@@ -181,6 +181,7 @@ function billsAndTxs(client, session, cb) {
 }
 
 function computeSendAmount(tx, totals) {
+  console.log('DEBUG10')
   var fiatRemaining = (tx.fiat || totals.billsFiat) - totals.txFiat;
   var satoshisRemaining = (tx.satoshis || totals.billsSatoshis) -
     totals.txSatoshis;
@@ -303,6 +304,8 @@ function insertTx(client, session, incoming, tx, satoshis, fiat, stage,
     tx.error
   ];
 
+  console.log('DEBUG11')
+
   query(client, getInsertQuery('transactions', fields, true), values,
       function(err, results) {
     if (err) return cb(err);
@@ -347,6 +350,7 @@ exports.addOutgoingTx = function addOutgoingTx(session, tx, cb) {
     if (cerr) return cb(cerr);
     async.series([
       async.apply(silentQuery, client, 'BEGIN'),
+      async.apply(silentQuery, client, 'LOCK TABLE transactions NOWAIT'),
       async.apply(insertOutgoingCompleteTx, client, session, tx),
       async.apply(removePendingTx, client, session),
       async.apply(buildOutgoingTx, client, session, tx)
@@ -357,7 +361,7 @@ exports.addOutgoingTx = function addOutgoingTx(session, tx, cb) {
       }
       silentQuery(client, 'COMMIT', [], function() {
         done();
-        var toSend = results[3];
+        var toSend = results[4];
         cb(null, toSend);
       });
     });
diff --git a/test/plugins.js b/test/plugins.js
index bf8aeaa4..206a7e41 100644
--- a/test/plugins.js
+++ b/test/plugins.js
@@ -192,7 +192,7 @@ describe('Plugins', function() {
     describe('Send Bitcoins', function() {
 
       before(function() {
-        plugins.trade({currency: 'USD', satoshis: 1e7}, db.FINGERPRINT_NEW);
+        plugins.trade('123', {currency: 'USD', satoshis: 1e7, toAddress: '1xxx'}, function() {});
       });
 
       it('should send bitcoins successfully', function(done) {