diff --git a/test/functional/mempool_reorg.py b/test/functional/mempool_reorg.py
index f09a1a9d6d..95cec7d698 100755
--- a/test/functional/mempool_reorg.py
+++ b/test/functional/mempool_reorg.py
@@ -1,111 +1,111 @@
 #!/usr/bin/env python3
 # Copyright (c) 2014-2016 The Bitcoin Core developers
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #
 # Test re-org scenarios with a mempool that contains transactions
 # that spend (directly or indirectly) coinbase transactions.
 #
 
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.util import *
 
 # Create one-input, one-output, no-fee transaction:
 
 
 class MempoolCoinbaseTest(BitcoinTestFramework):
     def set_test_params(self):
         self.num_nodes = 2
-        self.extra_args = [["-checkmempool"]] * 2
+        self.extra_args = [["-checkmempool", "-monolithactivationtime=0"]] * 2
 
     alert_filename = None  # Set by setup_network
 
     def run_test(self):
         # Start with a 200 block chain
         assert_equal(self.nodes[0].getblockcount(), 200)
 
         # Mine four blocks. After this, nodes[0] blocks
         # 101, 102, and 103 are spend-able.
         new_blocks = self.nodes[1].generate(4)
         self.sync_all()
 
         node0_address = self.nodes[0].getnewaddress()
         node1_address = self.nodes[1].getnewaddress()
 
         # Three scenarios for re-orging coinbase spends in the memory pool:
         # 1. Direct coinbase spend  :  spend_101
         # 2. Indirect (coinbase spend in chain, child in mempool) : spend_102 and spend_102_1
         # 3. Indirect (coinbase and child both in chain) : spend_103 and spend_103_1
         # Use invalidatblock to make all of the above coinbase spends invalid (immature coinbase),
         # and make sure the mempool code behaves correctly.
         b = [self.nodes[0].getblockhash(n) for n in range(101, 105)]
         coinbase_txids = [self.nodes[0].getblock(h)['tx'][0] for h in b]
         spend_101_raw = create_tx(
             self.nodes[0], coinbase_txids[1], node1_address, 49.99)
         spend_102_raw = create_tx(
             self.nodes[0], coinbase_txids[2], node0_address, 49.99)
         spend_103_raw = create_tx(
             self.nodes[0], coinbase_txids[3], node0_address, 49.99)
 
         # Create a transaction which is time-locked to two blocks in the future
         timelock_tx = self.nodes[0].createrawtransaction(
             [{"txid": coinbase_txids[0], "vout": 0}], {node0_address: 49.99})
         # Set the time lock
         timelock_tx = timelock_tx.replace("ffffffff", "11111191", 1)
         timelock_tx = timelock_tx[:-8] + \
             hex(self.nodes[0].getblockcount() + 2)[2:] + "000000"
         timelock_tx = self.nodes[0].signrawtransaction(timelock_tx)["hex"]
         # This will raise an exception because the timelock transaction is too immature to spend
         assert_raises_rpc_error(-26, "bad-txns-nonfinal",
                                 self.nodes[0].sendrawtransaction, timelock_tx)
 
         # Broadcast and mine spend_102 and 103:
         spend_102_id = self.nodes[0].sendrawtransaction(spend_102_raw)
         spend_103_id = self.nodes[0].sendrawtransaction(spend_103_raw)
         self.nodes[0].generate(1)
         # Time-locked transaction is still too immature to spend
         assert_raises_rpc_error(-26, 'bad-txns-nonfinal',
                                 self.nodes[0].sendrawtransaction, timelock_tx)
 
         # Create 102_1 and 103_1:
         spend_102_1_raw = create_tx(
             self.nodes[0], spend_102_id, node1_address, 49.98)
         spend_103_1_raw = create_tx(
             self.nodes[0], spend_103_id, node1_address, 49.98)
 
         # Broadcast and mine 103_1:
         spend_103_1_id = self.nodes[0].sendrawtransaction(spend_103_1_raw)
         last_block = self.nodes[0].generate(1)
         # Time-locked transaction can now be spent
         timelock_tx_id = self.nodes[0].sendrawtransaction(timelock_tx)
 
         # ... now put spend_101 and spend_102_1 in memory pools:
         spend_101_id = self.nodes[0].sendrawtransaction(spend_101_raw)
         spend_102_1_id = self.nodes[0].sendrawtransaction(spend_102_1_raw)
 
         self.sync_all()
 
         assert_equal(set(self.nodes[0].getrawmempool()), {
                      spend_101_id, spend_102_1_id, timelock_tx_id})
 
         for node in self.nodes:
             node.invalidateblock(last_block[0])
         # Time-locked transaction is now too immature and has been removed from the mempool
         # spend_103_1 has been re-orged out of the chain and is back in the mempool
         assert_equal(set(self.nodes[0].getrawmempool()), {
                      spend_101_id, spend_102_1_id, spend_103_1_id})
 
         # Use invalidateblock to re-org back and make all those coinbase spends
         # immature/invalid:
         for node in self.nodes:
             node.invalidateblock(new_blocks[0])
 
         self.sync_all()
 
         # mempool should be empty.
         assert_equal(set(self.nodes[0].getrawmempool()), set())
 
 
 if __name__ == '__main__':
     MempoolCoinbaseTest().main()