diff --git a/test/functional/invalidblockrequest.py b/test/functional/invalidblockrequest.py
index e71cc63b3a..775d07e4d4 100755
--- a/test/functional/invalidblockrequest.py
+++ b/test/functional/invalidblockrequest.py
@@ -1,124 +1,134 @@
 #!/usr/bin/env python3
 # Copyright (c) 2015-2016 The Bitcoin Core developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 from test_framework.test_framework import ComparisonTestFramework
 from test_framework.util import *
 from test_framework.comptool import TestManager, TestInstance, RejectResult
 from test_framework.blocktools import *
 import copy
 import time
 
 
 '''
 In this test we connect to one node over p2p, and test block requests:
 1) Valid blocks should be requested and become chain tip.
 2) Invalid block with duplicated transaction should be re-requested.
 3) Invalid block with bad coinbase value should be rejected and not
 re-requested.
 '''
 
 # Use the ComparisonTestFramework with 1 node: only use --testbinary.
 
 
 class InvalidBlockRequestTest(ComparisonTestFramework):
 
     ''' Can either run this test as 1 node with expected answers, or two and compare them.
         Change the "outcome" variable from each TestInstance object to only do the comparison. '''
 
     def set_test_params(self):
         self.num_nodes = 1
         self.setup_clean_chain = True
 
     def run_test(self):
         test = TestManager(self, self.options.tmpdir)
         test.add_all_connections(self.nodes)
         self.tip = None
         self.block_time = None
         NetworkThread().start()  # Start up network handling in another thread
         test.run()
 
     def get_tests(self):
         if self.tip is None:
             self.tip = int("0x" + self.nodes[0].getbestblockhash(), 0)
         self.block_time = int(time.time()) + 1
 
         '''
         Create a new block with an anyone-can-spend coinbase
         '''
         height = 1
         block = create_block(
             self.tip, create_coinbase(height), self.block_time)
         self.block_time += 1
         block.solve()
         # Save the coinbase for later
         self.block1 = block
         self.tip = block.sha256
         height += 1
         yield TestInstance([[block, True]])
 
         '''
         Now we need that block to mature so we can spend the coinbase.
         '''
         test = TestInstance(sync_every_block=False)
         for i in range(100):
             block = create_block(
                 self.tip, create_coinbase(height), self.block_time)
             block.solve()
             self.tip = block.sha256
             self.block_time += 1
             test.blocks_and_transactions.append([block, True])
             height += 1
         yield test
 
         '''
         Now we use merkle-root malleability to generate an invalid block with
         same blockheader.
         Manufacture a block with 3 transactions (coinbase, spend of prior
         coinbase, spend of that spend).  Duplicate the 3rd transaction to
         leave merkle root and blockheader unchanged but invalidate the block.
         '''
         block2 = create_block(
             self.tip, create_coinbase(height), self.block_time)
         self.block_time += 1
 
         # b'0x51' is OP_TRUE
         tx1 = create_transaction(self.block1.vtx[0], 0, b'\x51', 50 * COIN)
         tx2 = create_transaction(tx1, 0, b'\x51', 50 * COIN)
 
         block2.vtx.extend([tx1, tx2])
         block2.hashMerkleRoot = block2.calc_merkle_root()
         block2.rehash()
         block2.solve()
         orig_hash = block2.sha256
         block2_orig = copy.deepcopy(block2)
 
         # Mutate block 2
         block2.vtx.append(tx2)
         assert_equal(block2.hashMerkleRoot, block2.calc_merkle_root())
         assert_equal(orig_hash, block2.rehash())
         assert(block2_orig.vtx != block2.vtx)
 
         self.tip = block2.sha256
         yield TestInstance([[block2, RejectResult(16, b'bad-txns-duplicate')], [block2_orig, True]])
         height += 1
 
+        # Check transactions for duplicate inputs
+        self.log.info("Test duplicate input block.")
+
+        block2_orig.vtx[2].vin.append(block2_orig.vtx[2].vin[0])
+        block2_orig.vtx[2].rehash()
+        block2_orig.hashMerkleRoot = block2_orig.calc_merkle_root()
+        block2_orig.rehash()
+        block2_orig.solve()
+        yield TestInstance([[block2_orig, RejectResult(16, b'bad-txns-inputs-duplicate')]])
+
         '''
         Make sure that a totally screwed up block is not valid.
         '''
         block3 = create_block(
             self.tip, create_coinbase(height), self.block_time)
         self.block_time += 1
         block3.vtx[0].vout[0].nValue = 100 * COIN  # Too high!
         block3.vtx[0].sha256 = None
         block3.vtx[0].calc_sha256()
         block3.hashMerkleRoot = block3.calc_merkle_root()
         block3.rehash()
         block3.solve()
 
         yield TestInstance([[block3, RejectResult(16, b'bad-cb-amount')]])
 
 
 if __name__ == '__main__':
     InvalidBlockRequestTest().main()