diff --git a/anki/models.py b/anki/models.py
index 01559a058..4c8633b53 100644
--- a/anki/models.py
+++ b/anki/models.py
@@ -3,7 +3,7 @@
 # License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
 
 import simplejson
-from anki.utils import intTime, hexifyID, joinFields, splitFields
+from anki.utils import intTime, hexifyID, joinFields, splitFields, ids2str
 from anki.lang import _
 
 # Models
@@ -278,68 +278,45 @@ select id from facts where mid = ?)""" % " ".join(map), self.id)
 
     # Model changing
     ##########################################################################
+    # - maps are ord->ord, and there should not be duplicate targets
+    # - newModel should be self if model is not changing
+    # - interface should ensure there's at least one remaining card
 
-    def changeModel(self, fids, newModel, fieldMap, cardMap):
-        raise Exception()
-        self.modSchema()
-        sfids = ids2str(fids)
-        # field remapping
-        if fieldMap:
-            seen = {}
-            for (old, new) in fieldMap.items():
-                seen[new] = 1
-                if new:
-                    # can rename
-                    self.db.execute("""
-update fdata set
-fmid = :new,
-ord = :ord
-where fmid = :old
-and fid in %s""" % sfids, new=new.id, ord=new.ord, old=old.id)
-                else:
-                    # no longer used
-                    self.db.execute("""
-delete from fdata where fid in %s
-and fmid = :id""" % sfids, id=old.id)
-            # new
-            for field in newModel.fields:
-                if field not in seen:
-                    d = [{'fid': f,
-                          'fmid': field.id,
-                          'ord': field.ord}
-                         for f in fids]
-                    self.db.executemany('''
-insert into fdata
-(fid, fmid, ord, value)
-values
-(:fid, :fmid, :ord, "")''', d)
-            # fact modtime
-            self.db.execute("""
-update facts set
-mod = :t,
-mid = :id
-where id in %s""" % sfids, t=time.time(), id=newModel.id)
-        # template remapping
-        toChange = []
-        for (old, new) in cardMap.items():
-            if not new:
-                # delete
-                self.db.execute("""
-delete from cards
-where tid = :cid and
-fid in %s""" % sfids, cid=old.id)
-            elif old != new:
-                # gather ids so we can rename x->y and y->x
-                ids = self.db.list("""
-select id from cards where
-tid = :id and fid in %s""" % sfids, id=old.id)
-                toChange.append((new, ids))
-        for (new, ids) in toChange:
-            self.db.execute("""
-update cards set
-tid = :new,
-ord = :ord
-where id in %s""" % ids2str(ids), new=new.id, ord=new.ord)
-        cardIds = self.db.list(
-            "select id from cards where fid in %s" %
-            ids2str(fids))
+    def changeModel(self, fids, newModel, fmap, cmap):
+        self.deck.modSchema()
+        assert newModel.id == self.id or (fmap and cmap)
+        if fmap:
+            self._changeFacts(fids, newModel, fmap)
+        if cmap:
+            self._changeCards(fids, newModel, cmap)
+
+    def _changeFacts(self, fids, newModel, map):
+        d = []
+        nfields = len(newModel.fields)
+        for (fid, flds) in self.deck.db.execute(
+            "select id, flds from facts where id in "+ids2str(fids)):
+            newflds = {}
+            flds = splitFields(flds)
+            for old, new in map.items():
+                newflds[new] = flds[old]
+            flds = []
+            for c in range(nfields):
+                flds.append(newflds.get(c, ""))
+            flds = joinFields(flds)
+            d.append(dict(fid=fid, flds=flds, mid=newModel.id))
+        self.deck.db.executemany(
+            "update facts set flds=:flds, mid=:mid where id = :fid", d)
+        self.deck.updateFieldCache(fids)
+
+    def _changeCards(self, fids, newModel, map):
+        d = []
+        deleted = []
+        for (cid, ord) in self.deck.db.execute(
+            "select id, ord from cards where fid in "+ids2str(fids)):
+            if map[ord] is not None:
+                d.append(dict(cid=cid, new=map[ord]))
+            else:
+                deleted.append(cid)
+        self.deck.db.executemany(
+            "update cards set ord=:new where id=:cid", d)
+        self.deck.delCards(deleted)
diff --git a/tests/test_models.py b/tests/test_models.py
index d8b551eaf..8c8483677 100644
--- a/tests/test_models.py
+++ b/tests/test_models.py
@@ -148,69 +148,66 @@ def test_cloze():
     assert d.addFact(f) == 1
 
 def test_modelChange():
-    print "model change"
-    return
     deck = getEmptyDeck()
-    m2 = deck.currentModel()
-    # taken from jp support plugin
-    m1 = Model(deck)
-    m1.name = "Japanese"
-    # field 1
-    fm = m1.newField()
-    fm['name'] = "Expression"
-    fm['req'] = True
-    fm['uniq'] = True
-    m1.addField(fm)
-    # field2
-    fm = m1.newField()
-    fm['name'] = "Meaning"
-    m1.addField(fm)
-    # field3
-    fm = m1.newField()
-    fm['name'] = "Reading"
-    m1.addField(fm)
-    # template1
-    t = Template(deck)
-    t.name = "Recognition"
-    t.qfmt = "{{Expression}}"
-    t.afmt = "{{Reading}}<br>{{Meaning}}"
-    m1.addTemplate(t)
-    # template2
-    t = Template(deck)
-    t.name = "Recall"
-    t.qfmt = "{{Meaning}}"
-    t.afmt = "{{Expression}}<br>{{Reading}}"
-    #t.active = False
-    m1.addTemplate(t)
-    deck.addModel(m1)
-
-    # add some facts
+    basic = deck.getModel(1)
+    cloze = deck.getModel(2)
+    # enable second template and add a fact
+    basic.templates[1]['actv'] = True
+    basic.flush()
     f = deck.newFact()
-    f['Expression'] = u'e'
-    f['Meaning'] = u'm'
-    f['Reading'] = u'r'
+    f['Front'] = u'f'
+    f['Back'] = u'b'
     deck.addFact(f)
-    f2 = deck.newFact()
-    f2['Expression'] = u'e2'
-    f2['Meaning'] = u'm2'
-    f2['Reading'] = u'r2'
-    deck.addFact(f2)
-
-    # convert to basic
-    assert deck.modelUseCount(m1) == 2
-    assert deck.modelUseCount(m2) == 0
-    assert deck.cardCount() == 4
-    assert deck.factCount() == 2
-    fmap = {m1.fields[0]: m2.fields[0],
-            m1.fields[1]: None,
-            m1.fields[2]: m2.fields[1]}
-    cmap = {m1.templates[0]: m2.templates[0],
-            m1.templates[1]: None}
-    deck.changeModel([f.id], m2, fmap, cmap)
-    assert deck.modelUseCount(m1) == 1
-    assert deck.modelUseCount(m2) == 1
-    assert deck.cardCount() == 3
-    assert deck.factCount() == 2
-    c = deck.getCard(deck.db.scalar("select id from cards where fid = ?", f.id))
-    assert stripHTML(c.q()) == u"e"
-    assert stripHTML(c.a()) == u"r"
+    # switch fields
+    map = {0: 1, 1: 0}
+    basic.changeModel([f.id], basic, map, None)
+    f.load()
+    assert f['Front'] == 'b'
+    assert f['Back'] == 'f'
+    # switch cards
+    c0 = f.cards()[0]
+    c1 = f.cards()[1]
+    assert stripHTML(c0.q()) == "b"
+    assert stripHTML(c1.q()) == "f"
+    assert c0.ord == 0
+    assert c1.ord == 1
+    basic.changeModel([f.id], basic, None, map)
+    f.load(); c0.load(); c1.load()
+    assert stripHTML(c0.q()) == "f"
+    assert stripHTML(c1.q()) == "b"
+    assert c0.ord == 1
+    assert c1.ord == 0
+    # .cards() returns cards in order
+    assert f.cards()[0].id == c1.id
+    # delete first card
+    map = {0: None, 1: 1}
+    basic.changeModel([f.id], basic, None, map)
+    f.load()
+    c0.load()
+    try:
+        c1.load()
+        assert 0
+    except TypeError:
+        pass
+    assert len(f.cards()) == 1
+    # an unmapped field becomes blank
+    assert f['Front'] == 'b'
+    assert f['Back'] == 'f'
+    basic.changeModel([f.id], basic, map, None)
+    f.load()
+    assert f['Front'] == ''
+    assert f['Back'] == 'f'
+    # another fact to try model conversion
+    f = deck.newFact()
+    f['Front'] = u'f2'
+    f['Back'] = u'b2'
+    deck.addFact(f)
+    assert basic.useCount() == 2
+    assert cloze.useCount() == 0
+    map = {0: 0, 1: 1}
+    basic.changeModel([f.id], cloze, map, map)
+    f.load()
+    assert f['Text'] == "f2"
+    assert f['Notes'] == "b2"
+    assert len(f.cards()) == 2
+    assert "b2" in f.cards()[0].a()