diff --git a/src/lib.rs b/src/lib.rs
index e8987b7..4a6c23c 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,4 +1,4 @@
-#![feature(path_absolute_method)]
+#![feature(path_absolute_method, never_type)]
 use std::path::{Path, PathBuf};
 use std::sync::OnceLock;
 
diff --git a/src/tftp/server.rs b/src/tftp/server.rs
index 35ec72c..2cf1f24 100644
--- a/src/tftp/server.rs
+++ b/src/tftp/server.rs
@@ -145,7 +145,7 @@ where
     Ok(())
 }
 
-pub async fn serve<F, Fut>(callback: F) -> Result<(), Error>
+pub async fn serve<F, Fut>(callback: F) -> Result<!, Error>
 where
     F: Fn(&str) -> Fut + Clone + Send + 'static,
     Fut: Future<Output = Option<Vec<u8>>> + Send + 'static,