diff --git a/lib/server.js b/lib/server.js
index 8675d11..6090b33 100644
--- a/lib/server.js
+++ b/lib/server.js
@@ -33,7 +33,7 @@ var storage, blockExplorer;
  * @constructor
  */
 function WalletService() {
-  if (!initialized) 
+  if (!initialized)
     throw new Error('Server not initialized');
 
   this.storage = storage;
@@ -358,8 +358,7 @@ WalletService.prototype._getUtxos = function(cb) {
     bc.getUnspentUtxos(addressStrs, function(err, inutxos) {
       if (err) return cb(err);
       var utxos = _.map(inutxos, function(i) {
-        var r = i.toObject();
-        return _.pick(r,['txid', 'vout', 'address', 'scriptPubKey', 'amount', 'satoshis']);
+        return _.pick(i, ['txid', 'vout', 'address', 'scriptPubKey', 'amount', 'satoshis']);
       });
       self.getPendingTxs({}, function(err, txps) {
         if (err) return cb(err);
diff --git a/test/integration/server.js b/test/integration/server.js
index d64fc6e..5b2ae94 100644
--- a/test/integration/server.js
+++ b/test/integration/server.js
@@ -88,18 +88,15 @@ helpers.toSatoshi = function(btc) {
 };
 
 // Amounts in satoshis 
-helpers.createUtxos = function(server, wallet, amounts, cb) {
-  var addresses = [];
+helpers.stubUtxos = function(server, wallet, amounts, cb) {
+  var amounts = [].concat(amounts);
 
-  async.each(amounts, function(a, next) {
+  async.map(amounts, function(a, next) {
       server.createAddress({}, function(err, address) {
-        addresses.push(address);
-        next(err);
+        next(err, address);
       });
     },
-    function(err) {
-      amounts = [].concat(amounts);
-
+    function(err, addresses) {
       var i = 0;
       var utxos = _.map(amounts, function(amount) {
         return {
@@ -110,32 +107,20 @@ helpers.createUtxos = function(server, wallet, amounts, cb) {
           address: addresses[i++].address,
         };
       });
+
+      blockExplorer.getUnspentUtxos = sinon.stub().callsArgWith(1, null, utxos);
+
       return cb(utxos);
     });
 };
 
-
-helpers.stubBlockExplorer = function(server, inUtxos, txid) {
-
-  var utxos = _.map(inUtxos, function(x) {
-    x.toObject = function() {
-      return this;
-    };
-    return x;
-  });
-
-  var bc = sinon.stub();
-  bc.getUnspentUtxos = sinon.stub().callsArgWith(1, null, utxos);
-
-  if (txid) {
-    bc.broadcast = sinon.stub().callsArgWith(1, null, txid);
-  } else {
-    bc.broadcast = sinon.stub().callsArgWith(1, 'broadcast error');
-  }
-
-  server._getBlockExplorer = sinon.stub().returns(bc);
+helpers.stubBroadcast = function(txid) {
+  blockExplorer.broadcast = sinon.stub().callsArgWith(1, null, txid);
 };
 
+helpers.stubBroadcastFail = function() {
+  blockExplorer.broadcast = sinon.stub().callsArgWith(1, 'broadcast error');
+};
 
 
 helpers.clientSign = function(tx, xprivHex) {
@@ -185,7 +170,7 @@ helpers.createProposalOpts = function(toAddress, amount, message, signingKey) {
   return opts;
 };
 
-var db, storage;
+var db, storage, blockExplorer;
 
 
 describe('Copay server', function() {
@@ -196,8 +181,11 @@ describe('Copay server', function() {
     storage = new Storage({
       db: db
     });
+    blockExplorer = sinon.stub();
+
     WalletService.initialize({
-      storage: storage
+      storage: storage,
+      blockExplorer: blockExplorer,
     });
     helpers.offset = 0;
   });
@@ -662,8 +650,7 @@ describe('Copay server', function() {
     });
 
     it('should create a tx', function(done) {
-      helpers.createUtxos(server, wallet, [100, 200], function(utxos) {
-        helpers.stubBlockExplorer(server, utxos);
+      helpers.stubUtxos(server, wallet, [100, 200], function() {
         var txOpts = helpers.createProposalOpts('18PzpUFkFZE8zKWUPvfykkTxmB9oMR8qP7', 80, 'some message', TestData.copayers[0].privKey);
         server.createTx(txOpts, function(err, tx) {
           should.not.exist(err);
@@ -687,8 +674,7 @@ describe('Copay server', function() {
 
 
     it('should fail to create tx with invalid proposal signature', function(done) {
-      helpers.createUtxos(server, wallet, [100, 200], function(utxos) {
-        helpers.stubBlockExplorer(server, utxos);
+      helpers.stubUtxos(server, wallet, [100, 200], function() {
         var txOpts = helpers.createProposalOpts('18PzpUFkFZE8zKWUPvfykkTxmB9oMR8qP7', 80, null, 'dummy');
 
         server.createTx(txOpts, function(err, tx) {
@@ -701,8 +687,7 @@ describe('Copay server', function() {
     });
 
     it('should fail to create tx with proposal signed by another copayer', function(done) {
-      helpers.createUtxos(server, wallet, [100, 200], function(utxos) {
-        helpers.stubBlockExplorer(server, utxos);
+      helpers.stubUtxos(server, wallet, [100, 200], function() {
         var txOpts = helpers.createProposalOpts('18PzpUFkFZE8zKWUPvfykkTxmB9oMR8qP7', 80, null, TestData.copayers[1].privKey);
 
         server.createTx(txOpts, function(err, tx) {
@@ -715,8 +700,7 @@ describe('Copay server', function() {
     });
 
     it('should fail to create tx for invalid address', function(done) {
-      helpers.createUtxos(server, wallet, [100, 200], function(utxos) {
-        helpers.stubBlockExplorer(server, utxos);
+      helpers.stubUtxos(server, wallet, [100, 200], function() {
         var txOpts = helpers.createProposalOpts('invalid address', 80, null, TestData.copayers[0].privKey);
 
         server.createTx(txOpts, function(err, tx) {
@@ -730,8 +714,7 @@ describe('Copay server', function() {
     });
 
     it('should fail to create tx for address of different network', function(done) {
-      helpers.createUtxos(server, wallet, [100, 200], function(utxos) {
-        helpers.stubBlockExplorer(server, utxos);
+      helpers.stubUtxos(server, wallet, [100, 200], function() {
         var txOpts = helpers.createProposalOpts('myE38JHdxmQcTJGP1ZiX4BiGhDxMJDvLJD', 80, null, TestData.copayers[0].privKey);
 
         server.createTx(txOpts, function(err, tx) {
@@ -745,8 +728,7 @@ describe('Copay server', function() {
     });
 
     it('should fail to create tx when insufficient funds', function(done) {
-      helpers.createUtxos(server, wallet, [100], function(utxos) {
-        helpers.stubBlockExplorer(server, utxos);
+      helpers.stubUtxos(server, wallet, [100], function() {
         var txOpts = helpers.createProposalOpts('18PzpUFkFZE8zKWUPvfykkTxmB9oMR8qP7', 120, null, TestData.copayers[0].privKey);
         server.createTx(txOpts, function(err, tx) {
           should.exist(err);
@@ -767,8 +749,7 @@ describe('Copay server', function() {
     });
 
     it('should fail to create tx when insufficient funds for fee', function(done) {
-      helpers.createUtxos(server, wallet, [100], function(utxos) {
-        helpers.stubBlockExplorer(server, utxos);
+      helpers.stubUtxos(server, wallet, [100], function() {
         var txOpts = helpers.createProposalOpts('18PzpUFkFZE8zKWUPvfykkTxmB9oMR8qP7', 100, null, TestData.copayers[0].privKey);
         server.createTx(txOpts, function(err, tx) {
           should.exist(err);
@@ -780,8 +761,7 @@ describe('Copay server', function() {
     });
 
     it('should fail to create tx for dust amount', function(done) {
-      helpers.createUtxos(server, wallet, [1], function(utxos) {
-        helpers.stubBlockExplorer(server, utxos);
+      helpers.stubUtxos(server, wallet, [1], function() {
         var txOpts = helpers.createProposalOpts('18PzpUFkFZE8zKWUPvfykkTxmB9oMR8qP7', 0.00000001, null, TestData.copayers[0].privKey);
         server.createTx(txOpts, function(err, tx) {
           should.exist(err);
@@ -793,8 +773,7 @@ describe('Copay server', function() {
     });
 
     it('should create tx when there is a pending tx and enough UTXOs', function(done) {
-      helpers.createUtxos(server, wallet, [10.1, 10.2, 10.3], function(utxos) {
-        helpers.stubBlockExplorer(server, utxos);
+      helpers.stubUtxos(server, wallet, [10.1, 10.2, 10.3], function() {
         var txOpts = helpers.createProposalOpts('18PzpUFkFZE8zKWUPvfykkTxmB9oMR8qP7', 12, null, TestData.copayers[0].privKey);
         server.createTx(txOpts, function(err, tx) {
           should.not.exist(err);
@@ -819,8 +798,7 @@ 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, [10.1, 10.2, 10.3], function(utxos) {
-        helpers.stubBlockExplorer(server, utxos);
+      helpers.stubUtxos(server, wallet, [10.1, 10.2, 10.3], function() {
         var txOpts = helpers.createProposalOpts('18PzpUFkFZE8zKWUPvfykkTxmB9oMR8qP7', 12, null, TestData.copayers[0].privKey);
         server.createTx(txOpts, function(err, tx) {
           should.not.exist(err);
@@ -847,10 +825,9 @@ describe('Copay server', function() {
 
     it('should create tx using different UTXOs for simultaneous requests', function(done) {
       var N = 5;
-      helpers.createUtxos(server, wallet, _.times(N, function() {
+      helpers.stubUtxos(server, wallet, _.times(N, function() {
         return 100;
       }), function(utxos) {
-        helpers.stubBlockExplorer(server, utxos);
         server.getBalance({}, function(err, balance) {
           should.not.exist(err);
           balance.totalAmount.should.equal(helpers.toSatoshi(N * 100));
@@ -887,8 +864,7 @@ describe('Copay server', function() {
         server = s;
         wallet = w;
         server.createAddress({}, function(err, address) {
-          helpers.createUtxos(server, wallet, _.range(1, 9), function(utxos) {
-            helpers.stubBlockExplorer(server, utxos);
+          helpers.stubUtxos(server, wallet, _.range(1, 9), function() {
             var txOpts = helpers.createProposalOpts('18PzpUFkFZE8zKWUPvfykkTxmB9oMR8qP7', 10, null, TestData.copayers[0].privKey);
             server.createTx(txOpts, function(err, tx) {
               should.not.exist(err);
@@ -937,8 +913,7 @@ describe('Copay server', function() {
         server = s;
         wallet = w;
         server.createAddress({}, function(err, address) {
-          helpers.createUtxos(server, wallet, _.range(1, 9), function(utxos) {
-            helpers.stubBlockExplorer(server, utxos);
+          helpers.stubUtxos(server, wallet, _.range(1, 9), function() {
             var txOpts = helpers.createProposalOpts('18PzpUFkFZE8zKWUPvfykkTxmB9oMR8qP7', 10, null, TestData.copayers[0].privKey);
             server.createTx(txOpts, function(err, tx) {
               should.not.exist(err);
@@ -1090,14 +1065,13 @@ describe('Copay server', function() {
 
 
   describe('#signTx and broadcast', function() {
-    var server, wallet, utxos;
+    var server, wallet;
     beforeEach(function(done) {
       helpers.createAndJoinWallet(1, 1, function(s, w) {
         server = s;
         wallet = w;
         server.createAddress({}, function(err, address) {
-          helpers.createUtxos(server, wallet, _.range(1, 9), function(inutxos) {
-            utxos = inutxos;
+          helpers.stubUtxos(server, wallet, _.range(1, 9), function() {
             done();
           });
         });
@@ -1105,7 +1079,7 @@ describe('Copay server', function() {
     });
 
     it('should sign and broadcast a tx', function(done) {
-      helpers.stubBlockExplorer(server, utxos, '1122334455');
+      helpers.stubBroadcast('1122334455');
       var txOpts = helpers.createProposalOpts('18PzpUFkFZE8zKWUPvfykkTxmB9oMR8qP7', 10, null, TestData.copayers[0].privKey);
       server.createTx(txOpts, function(err, txp) {
         should.not.exist(err);
@@ -1138,7 +1112,7 @@ describe('Copay server', function() {
 
 
     it('should keep tx as *accepted* if unable to broadcast it', function(done) {
-      helpers.stubBlockExplorer(server, utxos);
+      helpers.stubBroadcastFail();
       var txOpts = helpers.createProposalOpts('18PzpUFkFZE8zKWUPvfykkTxmB9oMR8qP7', 10, null, TestData.copayers[0].privKey);
       server.createTx(txOpts, function(err, txp) {
         should.not.exist(err);
@@ -1170,15 +1144,14 @@ describe('Copay server', function() {
   });
 
   describe('Tx proposal workflow', function() {
-    var server, wallet, utxos;
+    var server, wallet;
     beforeEach(function(done) {
       helpers.createAndJoinWallet(2, 3, function(s, w) {
         server = s;
         wallet = w;
         server.createAddress({}, function(err, address) {
-          helpers.createUtxos(server, wallet, _.range(1, 9), function(inUtxos) {
-            utxos = inUtxos;
-            helpers.stubBlockExplorer(server, utxos, '999');
+          helpers.stubUtxos(server, wallet, _.range(1, 9), function() {
+            helpers.stubBroadcast('999');
             done();
           });
         });
@@ -1250,7 +1223,6 @@ describe('Copay server', function() {
         },
         function(txp, next) {
           helpers.getAuthServer(wallet.copayers[1].id, function(server, wallet) {
-            helpers.stubBlockExplorer(server, utxos, '999');
             var signatures = helpers.clientSign(txp, TestData.copayers[1].xPrivKey);
             server.signTx({
               txProposalId: txpId,
@@ -1333,7 +1305,6 @@ describe('Copay server', function() {
         },
         function(next) {
           helpers.getAuthServer(wallet.copayers[1].id, function(server, wallet) {
-            helpers.stubBlockExplorer(server, utxos, '999');
             server.rejectTx({
               txProposalId: txpId,
               reason: 'some other reason'
@@ -1379,8 +1350,7 @@ describe('Copay server', function() {
         server = s;
         wallet = w;
         server.createAddress({}, function(err, address) {
-          helpers.createUtxos(server, wallet, _.range(10), function(utxos) {
-            helpers.stubBlockExplorer(server, utxos);
+          helpers.stubUtxos(server, wallet, _.range(10), function() {
             var txOpts = helpers.createProposalOpts('18PzpUFkFZE8zKWUPvfykkTxmB9oMR8qP7', 0.1, null, TestData.copayers[0].privKey);
             async.eachSeries(_.range(10), function(i, next) {
               clock.tick(10000);
@@ -1466,8 +1436,7 @@ describe('Copay server', function() {
         server = s;
         wallet = w;
         server.createAddress({}, function(err, address) {
-          helpers.createUtxos(server, wallet, helpers.toSatoshi(_.range(4)), function(utxos) {
-            helpers.stubBlockExplorer(server, utxos);
+          helpers.stubUtxos(server, wallet, helpers.toSatoshi(_.range(4)), function() {
             var txOpts = helpers.createProposalOpts('18PzpUFkFZE8zKWUPvfykkTxmB9oMR8qP7', 0.01, null, TestData.copayers[0].privKey);
             async.eachSeries(_.range(3), function(i, next) {
               server.createTx(txOpts, function(err, tx) {
@@ -1522,6 +1491,7 @@ describe('Copay server', function() {
 
     it('should notify sign and acceptance', function(done) {
       server.getPendingTxs({}, function(err, txs) {
+        helpers.stubBroadcastFail();
         var tx = txs[0];
         var signatures = helpers.clientSign(tx, TestData.copayers[0].xPrivKey);
         server.signTx({
@@ -1566,7 +1536,7 @@ describe('Copay server', function() {
       server.getPendingTxs({}, function(err, txs) {
         var tx = txs[2];
         var signatures = helpers.clientSign(tx, TestData.copayers[0].xPrivKey);
-        helpers.stubBlockExplorer(server, [], '1122334455');
+        helpers.stubBroadcast('1122334455');
         sinon.spy(server, 'emit');
         server.signTx({
           txProposalId: tx.id,
@@ -1600,8 +1570,7 @@ describe('Copay server', function() {
         wallet = w;
 
         server.createAddress({}, function(err, address) {
-          helpers.createUtxos(server, wallet, _.range(2), function(utxos) {
-            helpers.stubBlockExplorer(server, utxos);
+          helpers.stubUtxos(server, wallet, _.range(2), function() {
             var txOpts = {
               toAddress: '18PzpUFkFZE8zKWUPvfykkTxmB9oMR8qP7',
               amount: helpers.toSatoshi(0.1),
@@ -1650,8 +1619,7 @@ describe('Copay server', function() {
           wallet = w;
 
           server.createAddress({}, function(err, address) {
-            helpers.createUtxos(server, wallet, _.range(2), function(utxos) {
-              helpers.stubBlockExplorer(server, utxos);
+            helpers.stubUtxos(server, wallet, _.range(2), function() {
               var txOpts = {
                 toAddress: '18PzpUFkFZE8zKWUPvfykkTxmB9oMR8qP7',
                 amount: helpers.toSatoshi(0.1),
@@ -1685,8 +1653,7 @@ describe('Copay server', function() {
         server = s;
         wallet = w;
         server.createAddress({}, function(err, address) {
-          helpers.createUtxos(server, wallet, [100, 200], function(utxos) {
-            helpers.stubBlockExplorer(server, utxos);
+          helpers.stubUtxos(server, wallet, [100, 200], function() {
             var txOpts = helpers.createProposalOpts('18PzpUFkFZE8zKWUPvfykkTxmB9oMR8qP7', 80, 'some message', TestData.copayers[0].privKey);
             server.createTx(txOpts, function(err, tx) {
               server.getPendingTxs({}, function(err, txs) {