diff --git a/src/main.rs b/src/main.rs
index 2e18b73..f4c34bc 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -20,6 +20,10 @@ impl file_rpc::Server for Serv {
 
     fn close(&self, _fd: u64) {
     }
+
+    fn size(&self, _fd: u64) -> Option<u64> {
+        None
+    }
 }
 
 fn main() {