diff --git a/src/backup/chunk_store.rs b/src/backup/chunk_store.rs
index b5c32903..582f514f 100644
--- a/src/backup/chunk_store.rs
+++ b/src/backup/chunk_store.rs
@@ -181,6 +181,7 @@ impl ChunkStore {
         let digest_str = tools::digest_to_hex(&digest);
         chunk_path.push(&digest_str);
 
+        buffer.clear();
         let f = std::fs::File::open(&chunk_path)?;
         let mut decoder = lz4::Decoder::new(f)?;