diff --git a/.gitignore b/.gitignore
index 465aa8a..34b12be 100644
--- a/.gitignore
+++ b/.gitignore
@@ -28,4 +28,5 @@ node_modules
 .lock-wscript
 
 *.swp
-out/
\ No newline at end of file
+out/
+db/
\ No newline at end of file
diff --git a/lib/server.js b/lib/server.js
index 6ac2dd3..bf07053 100644
--- a/lib/server.js
+++ b/lib/server.js
@@ -88,7 +88,8 @@ CopayServer.prototype.createWallet = function(opts, cb) {
   var self = this,
     pubKey;
 
-  if (!Utils.checkRequired(opts, ['name', 'm', 'n', 'pubKey'])) return cb(new ClientError('Required argument missing'));
+  if (!Utils.checkRequired(opts, ['name', 'm', 'n', 'pubKey']))
+    return cb(new ClientError('Required argument missing'));
 
   if (_.isEmpty(opts.name)) return cb(new ClientError('Invalid wallet name'));
   if (!Wallet.verifyCopayerLimits(opts.m, opts.n))
@@ -154,7 +155,8 @@ CopayServer.prototype._verifySignature = function(text, signature, pubKey) {
 CopayServer.prototype.joinWallet = function(opts, cb) {
   var self = this;
 
-  if (!Utils.checkRequired(opts, ['walletId', 'name', 'xPubKey', 'xPubKeySignature'])) return cb(new ClientError('Required argument missing'));
+  if (!Utils.checkRequired(opts, ['walletId', 'name', 'xPubKey', 'xPubKeySignature']))
+    return cb(new ClientError('Required argument missing'));
 
   if (_.isEmpty(opts.name)) return cb(new ClientError('Invalid copayer name'));
 
@@ -236,7 +238,8 @@ CopayServer.prototype.getAddresses = function(opts, cb) {
 CopayServer.prototype.verifyMessageSignature = function(opts, cb) {
   var self = this;
 
-  if (!Utils.checkRequired(opts, ['message', 'signature'])) return cb(new ClientError('Required argument missing'));
+  if (!Utils.checkRequired(opts, ['message', 'signature']))
+    return cb(new ClientError('Required argument missing'));
 
   self.getWallet({}, function(err, wallet) {
     if (err) return cb(err);
@@ -389,7 +392,8 @@ CopayServer.prototype._selectUtxos = function(txp, utxos) {
 CopayServer.prototype.createTx = function(opts, cb) {
   var self = this;
 
-  if (!Utils.checkRequired(opts, ['toAddress', 'amount'])) return cb(new ClientError('Required argument missing'));
+  if (!Utils.checkRequired(opts, ['toAddress', 'amount']))
+    return cb(new ClientError('Required argument missing'));
 
   Utils.runLocked(self.walletId, cb, function(cb) {
     self.getWallet({}, function(err, wallet) {
@@ -496,25 +500,22 @@ CopayServer.prototype.removePendingTx = function(opts, cb) {
 
   Utils.runLocked(self.walletId, cb, function(cb) {
 
-    self.storage.fetchTx(self.walletId, opts.id, function(err, txp) {
+    self.getTx({
+      id: opts.id
+    }, function(err, txp) {
       if (err) return cb(err);
-      if (!txp)
-        return cb(new ClientError('Transaction proposal not found'));
 
       if (!txp.isPending())
         return cb(new ClientError('Transaction proposal not pending'));
 
 
       if (txp.creatorId !== self.copayerId)
-        return cb(new ClientError('Not allowed to erase this TX'));
+        return cb(new ClientError('Only creators can remove pending proposals'));
 
       var actors = txp.getActors();
 
-      if (actors.length > 1)
-        return cb(new ClientError('Not allowed to erase this TX'));
-
-      if (actors.length == 1 && actors[0] !== self.copayerId)
-        return cb(new ClientError('Not allowed to erase this TX'));
+      if (actors.length > 1 || (actors.length == 1 && actors[0] !== self.copayerId))
+        return cb(new ClientError('Cannot remove a proposal signed/rejected by other copayers'));
 
       self.storage.removeTx(self.walletId, opts.id, cb);
     });
@@ -539,7 +540,8 @@ CopayServer.prototype._broadcastTx = function(txp, cb) {
 CopayServer.prototype.signTx = function(opts, cb) {
   var self = this;
 
-  if (!Utils.checkRequired(opts, ['txProposalId', 'signatures'])) return cb(new ClientError('Required argument missing'));
+  if (!Utils.checkRequired(opts, ['txProposalId', 'signatures']))
+    return cb(new ClientError('Required argument missing'));
 
   self.getWallet({}, function(err, wallet) {
     if (err) return cb(err);
@@ -548,7 +550,6 @@ CopayServer.prototype.signTx = function(opts, cb) {
       id: opts.txProposalId
     }, function(err, txp) {
       if (err) return cb(err);
-      if (!txp) return cb(new ClientError('Transaction proposal not found'));
 
       var action = _.find(txp.actions, {
         copayerId: self.copayerId
@@ -596,13 +597,14 @@ CopayServer.prototype.signTx = function(opts, cb) {
 CopayServer.prototype.rejectTx = function(opts, cb) {
   var self = this;
 
-  if (!Utils.checkRequired(opts, ['txProposalId'])) return cb(new ClientError('Required argument missing'));
+  if (!Utils.checkRequired(opts, ['txProposalId']))
+    return cb(new ClientError('Required argument missing'));
 
   self.getTx({
     id: opts.txProposalId
   }, function(err, txp) {
     if (err) return cb(err);
-    if (!txp) return cb(new ClientError('Transaction proposal not found'));
+
     var action = _.find(txp.actions, {
       copayerId: self.copayerId
     });
diff --git a/lib/utils.js b/lib/utils.js
index 905d798..b39fb7a 100644
--- a/lib/utils.js
+++ b/lib/utils.js
@@ -7,6 +7,8 @@ var Utils = {};
 Utils.runLocked = function(token, cb, task) {
   var self = this;
 
+  $.shouldBeDefined(token);
+
   Lock.get(token, function(lock) {
     var _cb = function() {
       cb.apply(null, arguments);
diff --git a/test/integration.js b/test/integration.js
index 1f632a3..9e2aa30 100644
--- a/test/integration.js
+++ b/test/integration.js
@@ -104,7 +104,7 @@ helpers.createUtxos = function(server, wallet, amounts, cb) {
         return {
           txid: helpers.randomTXID(),
           vout: Math.floor((Math.random() * 10) + 1),
-          satoshis: amount,
+          satoshis: helpers.toSatoshi(amount),
           scriptPubKey: addresses[i].getScriptPubKey(wallet.m).toBuffer().toString('hex'),
           address: addresses[i++].address,
         };
@@ -570,7 +570,7 @@ describe('Copay server', function() {
     });
 
     it('should create a tx', function(done) {
-      helpers.createUtxos(server, wallet, helpers.toSatoshi([100, 200]), function(utxos) {
+      helpers.createUtxos(server, wallet, [100, 200], function(utxos) {
         helpers.stubBlockExplorer(server, utxos);
         var txOpts = helpers.createProposalOpts('18PzpUFkFZE8zKWUPvfykkTxmB9oMR8qP7', 80, 'some message', copayerPriv[0].privKey);
         server.createTx(txOpts, function(err, tx) {
@@ -625,7 +625,7 @@ describe('Copay server', function() {
     });
 
     it('should fail to create tx for address invalid address', function(done) {
-      helpers.createUtxos(server, wallet, helpers.toSatoshi([100, 200]), function(utxos) {
+      helpers.createUtxos(server, wallet, [100, 200], function(utxos) {
         helpers.stubBlockExplorer(server, utxos);
         var txOpts = helpers.createProposalOpts('invalid address', 80, null, copayerPriv[0].privKey);
 
@@ -640,7 +640,7 @@ describe('Copay server', function() {
     });
 
     it('should fail to create tx for address of different network', function(done) {
-      helpers.createUtxos(server, wallet, helpers.toSatoshi([100, 200]), function(utxos) {
+      helpers.createUtxos(server, wallet, [100, 200], function(utxos) {
         helpers.stubBlockExplorer(server, utxos);
         var txOpts = helpers.createProposalOpts('myE38JHdxmQcTJGP1ZiX4BiGhDxMJDvLJD', 80, null, copayerPriv[0].privKey);
 
@@ -655,7 +655,7 @@ describe('Copay server', function() {
     });
 
     it('should fail to create tx when insufficient funds', function(done) {
-      helpers.createUtxos(server, wallet, helpers.toSatoshi([100]), function(utxos) {
+      helpers.createUtxos(server, wallet, [100], function(utxos) {
         helpers.stubBlockExplorer(server, utxos);
         var txOpts = helpers.createProposalOpts('18PzpUFkFZE8zKWUPvfykkTxmB9oMR8qP7', 120, null, copayerPriv[0].privKey);
         server.createTx(txOpts, function(err, tx) {
@@ -680,7 +680,7 @@ describe('Copay server', function() {
     it.skip('should fail to create tx for dust amount', function(done) {});
 
     it('should create tx when there is a pending tx and enough UTXOs', function(done) {
-      helpers.createUtxos(server, wallet, helpers.toSatoshi([10.1, 10.2, 10.3]), function(utxos) {
+      helpers.createUtxos(server, wallet, [10.1, 10.2, 10.3], function(utxos) {
         helpers.stubBlockExplorer(server, utxos);
         var txOpts = helpers.createProposalOpts('18PzpUFkFZE8zKWUPvfykkTxmB9oMR8qP7', 12, null, copayerPriv[0].privKey);
         server.createTx(txOpts, function(err, tx) {
@@ -706,7 +706,7 @@ describe('Copay server', function() {
     });
 
     it('should fail to create tx when there is a pending tx and not enough UTXOs', function(done) {
-      helpers.createUtxos(server, wallet, helpers.toSatoshi([10.1, 10.2, 10.3]), function(utxos) {
+      helpers.createUtxos(server, wallet, [10.1, 10.2, 10.3], function(utxos) {
         helpers.stubBlockExplorer(server, utxos);
         var txOpts = helpers.createProposalOpts('18PzpUFkFZE8zKWUPvfykkTxmB9oMR8qP7', 12, null, copayerPriv[0].privKey);
         server.createTx(txOpts, function(err, tx) {
@@ -734,9 +734,9 @@ describe('Copay server', function() {
 
     it('should create tx using different UTXOs for simultaneous requests', function(done) {
       var N = 5;
-      helpers.createUtxos(server, wallet, helpers.toSatoshi(_.times(N, function() {
+      helpers.createUtxos(server, wallet, _.times(N, function() {
         return 100;
-      })), function(utxos) {
+      }), function(utxos) {
         helpers.stubBlockExplorer(server, utxos);
         server.getBalance({}, function(err, balance) {
           should.not.exist(err);
@@ -776,7 +776,7 @@ describe('Copay server', function() {
         copayerPriv = c;
         copayerIds = ids;
         server.createAddress({}, function(err, address) {
-          helpers.createUtxos(server, wallet, helpers.toSatoshi([1, 2, 3, 4, 5, 6, 7, 8]), function(utxos) {
+          helpers.createUtxos(server, wallet, _.range(1, 9), function(utxos) {
             helpers.stubBlockExplorer(server, utxos);
             var txOpts = helpers.createProposalOpts('18PzpUFkFZE8zKWUPvfykkTxmB9oMR8qP7', 10, null, copayerPriv[0].privKey);
             server.createTx(txOpts, function(err, tx) {
@@ -826,7 +826,7 @@ describe('Copay server', function() {
         copayerPriv = c;
         copayerIds = ids;
         server.createAddress({}, function(err, address) {
-          helpers.createUtxos(server, wallet, helpers.toSatoshi([1, 2, 3, 4, 5, 6, 7, 8]), function(utxos) {
+          helpers.createUtxos(server, wallet, _.range(1, 9), function(utxos) {
             helpers.stubBlockExplorer(server, utxos);
             var txOpts = helpers.createProposalOpts('18PzpUFkFZE8zKWUPvfykkTxmB9oMR8qP7', 10, null, copayerPriv[0].privKey);
             server.createTx(txOpts, function(err, tx) {
@@ -968,7 +968,7 @@ describe('Copay server', function() {
         wallet = w;
         copayerPriv = c;
         server.createAddress({}, function(err, address) {
-          helpers.createUtxos(server, wallet, helpers.toSatoshi([1, 2, 3, 4, 5, 6, 7, 8]), function(inutxos) {
+          helpers.createUtxos(server, wallet, _.range(1, 9), function(inutxos) {
             utxos = inutxos;
             done();
           });
@@ -1042,7 +1042,7 @@ describe('Copay server', function() {
         wallet = w;
         copayerPriv = c;
         server.createAddress({}, function(err, address) {
-          helpers.createUtxos(server, wallet, helpers.toSatoshi([1, 2, 3, 4, 5, 6, 7, 8]), function(inutxos) {
+          helpers.createUtxos(server, wallet, _.range(1, 9), function(inutxos) {
             utxos = inutxos;
             done();
           });
@@ -1090,7 +1090,7 @@ describe('Copay server', function() {
         wallet = w;
         copayerPriv = c;
         server.createAddress({}, function(err, address) {
-          helpers.createUtxos(server, wallet, helpers.toSatoshi(_.range(10)), function(utxos) {
+          helpers.createUtxos(server, wallet, _.range(10), function(utxos) {
             helpers.stubBlockExplorer(server, utxos);
             var txOpts = helpers.createProposalOpts('18PzpUFkFZE8zKWUPvfykkTxmB9oMR8qP7', 0.1, null, copayerPriv[0].privKey);
             async.eachSeries(_.range(10), function(i, next) {
@@ -1177,7 +1177,7 @@ describe('Copay server', function() {
         wallet = w;
 
         server.createAddress({}, function(err, address) {
-          helpers.createUtxos(server, wallet, helpers.toSatoshi(_.range(2)), function(utxos) {
+          helpers.createUtxos(server, wallet, _.range(2), function(utxos) {
             helpers.stubBlockExplorer(server, utxos);
             var txOpts = {
               toAddress: '18PzpUFkFZE8zKWUPvfykkTxmB9oMR8qP7',
@@ -1225,7 +1225,7 @@ describe('Copay server', function() {
           wallet = w;
 
           server.createAddress({}, function(err, address) {
-            helpers.createUtxos(server, wallet, helpers.toSatoshi(_.range(2)), function(utxos) {
+            helpers.createUtxos(server, wallet, _.range(2), function(utxos) {
               helpers.stubBlockExplorer(server, utxos);
               var txOpts = {
                 toAddress: '18PzpUFkFZE8zKWUPvfykkTxmB9oMR8qP7',
@@ -1261,7 +1261,7 @@ describe('Copay server', function() {
         wallet = w;
         copayerPriv = c;
         server.createAddress({}, function(err, address) {
-          helpers.createUtxos(server, wallet, helpers.toSatoshi([100, 200]), function(utxos) {
+          helpers.createUtxos(server, wallet, [100, 200], function(utxos) {
             helpers.stubBlockExplorer(server, utxos);
             var txOpts = helpers.createProposalOpts('18PzpUFkFZE8zKWUPvfykkTxmB9oMR8qP7', 80, 'some message', copayerPriv[0].privKey);
             server.createTx(txOpts, function(err, tx) {
@@ -1310,7 +1310,7 @@ describe('Copay server', function() {
         server2.removePendingTx({
           id: txp.id
         }, function(err) {
-          err.message.should.contain('Not allowed');
+          err.message.should.contain('creators');
           server2.getPendingTxs({}, function(err, txs) {
             txs.length.should.equal(1);
             done();
@@ -1330,7 +1330,7 @@ describe('Copay server', function() {
           server.removePendingTx({
             id: txp.id
           }, function(err) {
-            err.message.should.contain('Not allowed');
+            err.message.should.contain('other copayers');
             done();
           });
         });