diff --git a/src/main.rs b/src/main.rs
index 7096662..7087c29 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -31,6 +31,10 @@ impl file_rpc::Server for Serv {
     fn size(&self, _fd: u64) -> Option<u64> {
         Some(self.initrd.len() as u64)
     }
+
+    fn dup(&self, fd: u64) -> Option<u64> {
+        Some(fd)
+    }
 }
 
 fn main() {