diff --git a/app/Main.hs b/app/Main.hs
index c651578..a0a0383 100644
--- a/app/Main.hs
+++ b/app/Main.hs
@@ -72,6 +72,7 @@ data AppS = AppS
   , appCursor   :: Int
   , appFocus    :: Maybe FilePath
   , appSubFiles :: [(FilePath, Integer)]
+  , appLenSub   :: Int
   , appMemo     :: IORef (IOHashMap FilePath [(FilePath, Integer)])
   , appRoot     :: FilePath
   }
@@ -133,6 +134,7 @@ sizeDir s = do
         appCursor = 0
       , appFocus = map fst subFiles !? 0
       , appSubFiles = subFiles
+      , appLenSub = length subFiles
       }
 
 changeDir :: AppS -> IO AppS
@@ -162,6 +164,7 @@ overDir s = do
                   , appCursor = 0
                   , appFocus = pure a
                   , appSubFiles = []
+                  , appLenSub = 0
                   }
 
 scroll :: ScrollDirection -> AppS -> AppS
@@ -174,7 +177,7 @@ scroll d s = s {
           case d of
             SUp   -> (-1)
             SDown -> 1
-        newCursor = clamp 0 (subtract 1 . length $ appSubFiles s) cursor
+        newCursor = clamp 0 (subtract 1 $ appLenSub s) cursor
         maybeNewPath = fst <$> appSubFiles s !? newCursor
 
 eventHandler :: BrickEvent () e -> EventM () AppS ()
@@ -213,6 +216,7 @@ initialState f i =
         , appSubFiles = []
         , appMemo = i
         , appRoot = f
+        , appLenSub = 0
         }
 
 main :: IO ()