diff --git a/src/Unused/Cache.hs b/src/Unused/Cache.hs
index a0bbc7d..bfdcc4e 100644
--- a/src/Unused/Cache.hs
+++ b/src/Unused/Cache.hs
@@ -16,6 +16,7 @@ cached context f =
     fromCache = maybe (writeCache =<< liftReaderT f) return =<< readCache
 
 writeCache :: ToRecord a => [a] -> ReaderT String IO [a]
+writeCache [] = return []
 writeCache contents = do
     liftReaderT $ createDirectoryIfMissing True cacheDirectory
     fileName <- ask