diff --git a/little-hesinde/src/cache.rs b/little-hesinde/src/cache.rs
index ddf01e2..91965aa 100644
--- a/little-hesinde/src/cache.rs
+++ b/little-hesinde/src/cache.rs
@@ -51,6 +51,7 @@ fn hash_to_path(hash: GenericArray<u8, U32>, cache_path: &Path) -> Result<PathBu
         .join(remaining_segment))
 }
 
+/// Create a thumbnail for `cover_path` at `thumbnail_path`.
 fn create_thumbnail(cover_path: &Path, thumbnail_path: &Path) -> Result<(), CacheError> {
     debug!("creating thumbnail for {}", cover_path.to_string_lossy());
     let folders = thumbnail_path