diff --git a/authfs/src/file/remote_file.rs b/authfs/src/file/remote_file.rs
index f2ac23f..9d614f5 100644
--- a/authfs/src/file/remote_file.rs
+++ b/authfs/src/file/remote_file.rs
@@ -41,8 +41,9 @@
         .unwrap()
         .readFile(remote_fd, offset, buf.len() as i32)
         .map_err(|e| io::Error::new(io::ErrorKind::Other, e.get_description()))?;
-    buf.copy_from_slice(&chunk);
-    Ok(min(buf.len(), chunk.len()))
+    let size = min(buf.len(), chunk.len());
+    buf[..size].copy_from_slice(&chunk[..size]);
+    Ok(size)
 }
 
 pub struct RemoteFileReader {
@@ -87,8 +88,9 @@
             .unwrap()
             .readFsverityMerkleTree(self.file_fd, offset, buf.len() as i32)
             .map_err(|e| io::Error::new(io::ErrorKind::Other, e.get_description()))?;
-        buf.copy_from_slice(&chunk);
-        Ok(min(buf.len(), chunk.len()))
+        let size = min(buf.len(), chunk.len());
+        buf[..size].copy_from_slice(&chunk[..size]);
+        Ok(size)
     }
 }