diff --git a/test/functional/feature_bip68_sequence.py b/test/functional/feature_bip68_sequence.py
--- a/test/functional/feature_bip68_sequence.py
+++ b/test/functional/feature_bip68_sequence.py
@@ -388,7 +388,10 @@
             block.solve()
             tip = block.sha256
             height += 1
-            self.nodes[0].submitblock(ToHex(block))
+            assert_equal(
+                None if i == 1 else 'inconclusive',
+                self.nodes[0].submitblock(
+                    ToHex(block)))
             cur_time += 1
 
         mempool = self.nodes[0].getrawmempool()
@@ -457,7 +460,7 @@
         block.rehash()
         block.solve()
 
-        self.nodes[0].submitblock(ToHex(block))
+        assert_equal(None, self.nodes[0].submitblock(ToHex(block)))
         assert_equal(self.nodes[0].getbestblockhash(), block.hash)
 
     def activateCSV(self):