diff --git a/lib/server.js b/lib/server.js
index de7d8fa..08431ec 100644
--- a/lib/server.js
+++ b/lib/server.js
@@ -567,6 +567,12 @@ WalletService.prototype.joinWallet = function(opts, cb) {
   if (_.isEmpty(opts.name))
     return cb(new ClientError('Invalid copayer name'));
 
+  try {
+    Bitcore.HDPublicKey(opts.xPubKey);
+  } catch (ex) {
+    return cb(new ClientError('Invalid extended public key'));
+  }
+
   opts.supportBIP44AndP2PKH = _.isBoolean(opts.supportBIP44AndP2PKH) ? opts.supportBIP44AndP2PKH : true;
 
   self.walletId = opts.walletId;
@@ -1275,7 +1281,7 @@ WalletService.prototype.createTx = function(opts, cb) {
         if (!canCreate) return cb(Errors.TX_CANNOT_CREATE);
 
         if (type != Model.TxProposal.Types.EXTERNAL) {
-		      var validationError = self._validateOutputs(opts, wallet);
+          var validationError = self._validateOutputs(opts, wallet);
           if (validationError) {
             return cb(validationError);
           }
diff --git a/test/integration/server.js b/test/integration/server.js
index fcdc364..2d3a9db 100644
--- a/test/integration/server.js
+++ b/test/integration/server.js
@@ -450,6 +450,21 @@ describe('Wallet service', function() {
       });
     });
 
+    it('should fail to join with invalid xPubKey', function(done) {
+      var copayerOpts = helpers.getSignedCopayerOpts({
+        walletId: walletId,
+        name: 'copayer 1',
+        xPubKey: 'invalid',
+        requestPubKey: TestData.copayers[0].pubKey_1H_0,
+      });
+      server.joinWallet(copayerOpts, function(err, result) {
+        should.not.exist(result);
+        should.exist(err);
+        err.message.should.contain('extended public key');
+        done();
+      });
+    });
+
     it('should fail to join with null signature', function(done) {
       var copayerOpts = {
         walletId: walletId,
@@ -2215,7 +2230,7 @@ describe('Wallet service', function() {
           should.not.exist(err);
           var inputs = [utxos[0], utxos[2]];
           var txOpts = helpers.createExternalProposalOpts('18PzpUFkFZE8zKWUPvfykkTxmB9oMR8qP7', 2.5,
-              TestData.copayers[0].privKey_1H_0, inputs);
+            TestData.copayers[0].privKey_1H_0, inputs);
           server.createTx(txOpts, function(err, tx) {
             should.not.exist(err);
             should.exist(tx);