diff --git a/mount/redox/scheme.rs b/mount/redox/scheme.rs
index 042d5a2e7c..a4ead40824 100644
--- a/mount/redox/scheme.rs
+++ b/mount/redox/scheme.rs
@@ -398,9 +398,13 @@ impl Scheme for FileScheme {
 
     /* Resource operations */
     #[allow(unused_variables)]
-    fn dup(&self, old_id: usize, _buf: &[u8]) -> Result<usize> {
+    fn dup(&self, old_id: usize, buf: &[u8]) -> Result<usize> {
         // println!("Dup {}", old_id);
 
+        if ! buf.is_empty() {
+            return Err(Error::new(ENOENT));
+        }
+
         let mut files = self.files.lock();
         let resource = if let Some(old_resource) = files.get(&old_id) {
             old_resource.dup()?