diff --git a/Database/Persist/MongoDB.hs b/Database/Persist/MongoDB.hs
--- a/Database/Persist/MongoDB.hs
+++ b/Database/Persist/MongoDB.hs
@@ -371,26 +371,6 @@
 keyToMongoIdField k = _id DB.:= (DB.ObjId $ keyToOid k)
 
 
-findAndModifyOne :: (Applicative m, Trans.MonadIO m)
-                 => DB.Collection
-                 -> DB.ObjectId -- ^ _id for query
-                 -> [DB.Field]  -- ^ updates
-                 -> DB.Action m (Either String DB.Document)
-findAndModifyOne coll objectId updates = do
-  result <- DB.runCommand [
-     "findAndModify" DB.:= DB.String coll,
-     "new" DB.:= DB.Bool True, -- return updated document, not original document
-     "query" DB.:= DB.Doc [_id DB.:= DB.ObjId objectId],
-     "update" DB.:= DB.Doc updates
-   ]
-  return $ case findErr result of
-    Nothing -> case DB.lookup "value" result of
-      Nothing -> Left "no value field"
-      Just doc -> Right doc
-    Just e -> Left e
-    where
-      findErr result = DB.lookup "err" =<< (DB.lookup "lastErrorObject" result)
-
 instance (Applicative m, Functor m, Trans.MonadIO m, MonadBaseControl IO m) => PersistQuery (DB.Action m) where
     update _ [] = return ()
     update key upds =
@@ -399,8 +379,9 @@
            $ updateFields upds
 
     updateGet key upds = do
-        result <- findAndModifyOne (unDBName $ entityDB t)
-                   (keyToOid key) (updateFields upds)
+        result <- DB.findAndModify (DB.select [keyToMongoIdField key]
+                     (unDBName $ entityDB t)
+                   ) (updateFields upds)
         case result of
           Left e -> err e
           Right doc -> do
diff --git a/persistent-mongoDB.cabal b/persistent-mongoDB.cabal
--- a/persistent-mongoDB.cabal
+++ b/persistent-mongoDB.cabal
@@ -1,5 +1,5 @@
 name:            persistent-mongoDB
-version:         1.2.1.2
+version:         1.2.2
 license:         MIT
 license-file:    LICENSE
 author:          Greg Weber <greg@gregweber.info>
@@ -25,7 +25,7 @@
                    , bytestring         >= 0.9
                    , conduit            >= 0.5.3
                    , resourcet          >= 0.3
-                   , mongoDB            >= 1.3     && < 1.4.1
+                   , mongoDB            >= 1.4.1   && < 1.5
                    , bson               >= 0.2     && < 0.3
                    , network            >= 2.2.1.7
                    , cereal             >= 0.3.0.0