diff --git a/src/Chart.hs b/src/Chart.hs
index 0054d01..4abdee9 100644
--- a/src/Chart.hs
+++ b/src/Chart.hs
@@ -42,14 +42,16 @@ newChart contract = do
         files <- liftIO $ listDirectory $ "cache" </> show con
         res <- forM files $ \cacheFileName -> do
           let fname = "cache" </> show con </> cacheFileName
-          ifM (liftIO $ doesFileExist $ fname)
+          ifM (liftIO $ doesFileExist fname)
               (bimap (\err -> cacheFileName <> ": "<> err) ((readMaybe $ dropExtension cacheFileName) :: Maybe Day,) <$> liftIO (eitherDecodeFileStrict' fname))
               (return $ Left $ "cachefile "<>cacheFileName<>" not found.")
         return $ partitionEithers res
     unless (null cacheErrors) $ forM_ cacheErrors $ \err -> logError (displayShow err)
-    let cacheData' :: HashMap Day (FingerTree TimePoint ChartPoint) = HM.fromList $ bimap (fromMaybe today) FT.fromList <$> cacheData
-    logError $ displayShow $ HM.keys cacheData'
-    c <- liftIO $ newTVarIO $ Chart con (fromMaybe FT.empty $ cacheData' HM.!? today) (HM.delete today cacheData') undefined defChartSettings [] Nothing False
+    let (unknownDates, cacheData') = partition (isNothing . fst) cacheData
+    unless (null unknownDates) $ logError $ display $ T.pack $ show (length unknownDates) <> " files had no parsable Date."
+    let cacheData'' :: HashMap Day (FingerTree TimePoint ChartPoint) = HM.fromList $ bimap (fromMaybe today) FT.fromList <$> cacheData'
+    logError $ displayShow $ HM.keys cacheData''
+    c <- liftIO $ newTVarIO $ Chart con (fromMaybe FT.empty $ cacheData'' HM.!? today) (HM.delete today cacheData'') undefined defChartSettings [] Nothing False
     tid <- liftIO $ forkIO $ fillChart app contract c
     liftIO $ atomically $ do
       modifyTVar' c (\Chart{..} -> let fillerThread = tid in Chart{..})
diff --git a/src/Run.hs b/src/Run.hs
index 0df3b44..4288a59 100644
--- a/src/Run.hs
+++ b/src/Run.hs
@@ -57,12 +57,12 @@ shutdownApp = do
     today <- liftIO $ utctDay <$> getCurrentTime
     liftIO $ unlessM (doesDirectoryExist $ "cache/" <> show chartContractID) $ createDirectory $ "cache/" <> show chartContractID
     let (_, chartData') = getUpdatedChartCache c (Just $ ChartSettings 5 Nothing Nothing)
-        merge a b = a <> b --TODO: merge duplicates!
-        newData = HM.alter (\case
-          Just t  -> Just (merge t chartData')
-          Nothing -> Just chartData') today (toList <$> chartHistData)
-        newData' = filter (\ChartPoint{..} -> 0 /= volume) <$> newData
-    forM_ (HM.toList newData') $ \(day, dat) -> do
+        newData = HM.toList
+                . fmap (filter (\ChartPoint{..} -> 0 /= volume))
+                . HM.alter (Just . maybe chartData' (<>chartData')) today
+                . fmap toList
+                $ chartHistData
+    forM_ newData $ \(day, dat) -> do
         liftIO $ encodeFile ("cache/" <> show chartContractID <> "/" <> show day <> ".json") dat
   logInfo $ display $ ppShow' settings'