diff --git a/chainsyncer/driver.py b/chainsyncer/driver.py
index c4b3080..32cae8f 100644
--- a/chainsyncer/driver.py
+++ b/chainsyncer/driver.py
@@ -92,6 +92,9 @@ class BlockPollSyncer(Syncer):
             if self.pre_callback != None:
                 self.pre_callback()
             while True and Syncer.running_global:
+                if start_tx > 0:
+                    start_tx -= 1
+                    continue
                 try:
                     block = self.get(conn)
                 except SyncDone as e:
@@ -108,8 +111,6 @@ class BlockPollSyncer(Syncer):
                     self.block_callback(block, None)
 
                 last_block = block
-                if start_tx > 0:
-                    block.txs = block.txs[start_tx:]
                 self.process(conn, block)
                 start_tx = 0
                 time.sleep(self.yield_delay)
@@ -121,8 +122,8 @@ class BlockPollSyncer(Syncer):
 class HeadSyncer(BlockPollSyncer):
 
     def process(self, conn, block):
-        logg.debug('process block {}'.format(block))
         (pair, fltr) = self.backend.get()
+        logg.debug('process block {} (backend {}:{})'.format(block, pair, fltr))
         i = pair[1] # set tx index from previous
         tx = None
         while True:
@@ -137,6 +138,7 @@ class HeadSyncer(BlockPollSyncer):
             tx.apply_receipt(rcpt)
     
             self.process_single(conn, block, tx)
+            self.backend.reset_filter()
                         
             i += 1
         
diff --git a/chainsyncer/unittest/base.py b/chainsyncer/unittest/base.py
index 7c38b04..5fd4b57 100644
--- a/chainsyncer/unittest/base.py
+++ b/chainsyncer/unittest/base.py
@@ -12,6 +12,13 @@ from chainsyncer.error import NoBlockForYou
 logg = logging.getLogger().getChild(__name__)
 
 
+
+class MockConn:
+
+    def do(self, o):
+        pass
+
+
 class MockTx:
 
     def __init__(self, index, tx_hash):
@@ -19,6 +26,10 @@ class MockTx:
         self.index = index
 
 
+    def apply_receipt(self, rcpt):
+        self.rcpt = rcpt
+
+
 class MockBlock:
 
     def __init__(self, number, txs):
@@ -54,13 +65,3 @@ class TestSyncer(HistorySyncer):
                 block_txs.append(add_0x(os.urandom(32).hex()))
      
         return MockBlock(block_height, block_txs)
-
-
-    # TODO: implement mock conn instead, and use HeadSyncer.process
-    def process(self, conn, block):
-        i = 0
-        for tx in block.txs:
-            self.process_single(conn, block, block.tx(i))
-            self.backend.reset_filter()
-            i += 1
-        self.backend.set(block.number + 1, 0)
diff --git a/tests/test_interrupt.py b/tests/test_interrupt.py
index f7aebab..238cdc9 100644
--- a/tests/test_interrupt.py
+++ b/tests/test_interrupt.py
@@ -14,6 +14,7 @@ from chainsyncer.backend.sql import SyncerBackend
 from tests.base import TestBase
 from chainsyncer.unittest.base import (
         MockBlock,
+        MockConn,
         TestSyncer,
         )
 
@@ -63,27 +64,28 @@ class TestInterrupt(TestBase):
         self.filters =  [
             CountFilter('foo'),
             CountFilter('bar'),
-            NaughtyCountExceptionFilter('xyzzy', 3),
+            NaughtyCountExceptionFilter('xyzzy', croak_on=3),
             CountFilter('baz'),
             ]
         self.backend = None
+        self.conn = MockConn()
         
 
     def assert_filter_interrupt(self):
        
-        syncer = TestSyncer(self.backend, [4, 2, 3])
+        syncer = TestSyncer(self.backend, [4, 3, 2])
 
         for fltr in self.filters:
             syncer.add_filter(fltr)
 
         try:
-            syncer.loop(0.1, None)
+            syncer.loop(0.1, self.conn)
         except RuntimeError:
             logg.info('caught croak')
             pass
         (pair, fltr) = self.backend.get()
         self.assertGreater(fltr, 0)
-        syncer.loop(0.1, None)
+        syncer.loop(0.1, self.conn)
 
         for fltr in self.filters:
             logg.debug('{} {}'.format(str(fltr), fltr.c))