diff --git a/anki/sync.py b/anki/sync.py
index df46ee761..ddcdada73 100644
--- a/anki/sync.py
+++ b/anki/sync.py
@@ -98,8 +98,11 @@ class SyncTools(object):
         "Sync two decks locally. Reimplement this for finer control."
         if not self.prepareSync(0):
             return
-        sums = self.summaries()
-        payload = self.genPayload(sums)
+        lsum = self.summary(self.deck.lastSync)
+        rsum = self.server.summary(self.deck.lastSync)
+        if not lsum or not rsum:
+            raise Exception("full sync required")
+        payload = self.genPayload((lsum, rsum))
         res = self.server.applyPayload(payload)
         self.applyPayloadReply(res)
         self.deck.reset()
@@ -111,15 +114,11 @@ class SyncTools(object):
         if self.localTime == self.remoteTime:
             return False
         l = self._lastSync(); r = self.server._lastSync()
-        # set lastSync to the lower of the two sides, and account for slow
-        # clocks & assume it took up to 10 seconds for the reply to arrive
-        self.deck.lastSync = min(l, r) - timediff - 10
+        # set lastSync to the lower of the two sides, account for slow clocks,
+        # and assume it took up to 10 seconds for the reply to arrive
+        self.deck.lastSync = max(0, min(l, r) - timediff - 10)
         return True
 
-    def summaries(self):
-        return (self.summary(self.deck.lastSync),
-                self.server.summary(self.deck.lastSync))
-
     def genPayload(self, summaries):
         (lsum, rsum) = summaries
         self.preSyncRefresh()
@@ -219,10 +218,11 @@ class SyncTools(object):
 
     def summary(self, lastSync):
         "Generate a full summary of modtimes for two-way syncing."
-        # client may have selected an earlier sync time
+        # if client may have selected an earlier sync time
         self.deck.lastSync = lastSync
-        # ensure we're flushed first
-        self.deck.s.flush()
+        # return early if there's been a schema change
+        if self.deck.getFloat("schemaMod") > lastSync:
+            return None
         return {
             # cards
             "cards": self.realLists(self.deck.s.all(
diff --git a/tests/test_sync.py b/tests/test_sync.py
index e852a71e9..3ed501b8f 100644
--- a/tests/test_sync.py
+++ b/tests/test_sync.py
@@ -133,7 +133,7 @@ def test_localsync_models():
     assert deck1.currentModel.cardModels[1].active == True
     deck2.currentModel.cardModels[1].active = False
     deck2.currentModel.setModified()
-    deck2.setModified()
+    deck2.flushMod()
     client.sync()
     assert deck1.currentModel.cardModels[1].active == False
     # remove a card model
@@ -144,25 +144,8 @@ def test_localsync_models():
     assert len(deck1.currentModel.cardModels) == 1
     client.sync()
     assert len(deck2.currentModel.cardModels) == 1
-    # add a field
-    c = deck1.getCard()
-    deck1.addFieldModel(c.fact.model, FieldModel(u"yo"))
-    deck1.s.refresh(c.fact)
-    assert len(c.fact.fields) == 3
-    assert c.fact['yo'] == u""
-    client.sync()
-    c2 = deck2.s.query(Card).get(c.id)
-    deck2.s.refresh(c2.fact)
-    assert c2.fact['yo'] == u""
-    # remove the field
-    assert "yo" in c2.fact.keys()
-    deck2.deleteFieldModel(c2.fact.model, c2.fact.model.fieldModels[2])
-    deck2.s.refresh(c2.fact)
-    assert "yo" not in c2.fact.keys()
-    client.sync()
-    deck1.s.refresh(c.fact)
-    assert "yo" not in c.fact.keys()
     # rename a field
+    c = deck1.getCard()
     assert u"Front" in c.fact.keys()
     deck1.renameFieldModel(deck1.currentModel,
                            deck1.currentModel.fieldModels[0],
@@ -257,28 +240,6 @@ def test_localsync_media():
     assert deck1.s.scalar("select count(1) from media") == 3
     assert deck2.s.scalar("select count(1) from media") == 3
 
-# One way syncing
-##########################################################################
-
-@nose.with_setup(setup_local, teardown)
-def test_oneway_simple():
-    assert deck1.s.scalar("select count(1) from cards") == 2
-    assert deck2.s.scalar("select count(1) from cards") == 2
-    assert deck1.cardCount == 2
-    assert deck2.cardCount == 2
-    assert deck1.s.scalar("select id from tags where tag = 'foo'")
-    assert not deck1.s.scalar("select id from tags where tag = 'bar'")
-    server.deckName = "dummy"
-    client.syncOneWay(0)
-    assert deck1.s.scalar("select count(1) from cards") == 4
-    assert deck2.s.scalar("select count(1) from cards") == 2
-    assert deck1.cardCount == 4
-    assert deck2.cardCount == 2
-    assert deck1.s.scalar("select id from tags where tag = 'foo'")
-    assert deck1.s.scalar("select id from tags where tag = 'bar'")
-    # should be a noop
-    client.syncOneWay(0)
-
 # Remote tests
 ##########################################################################