diff --git a/crates/sel4-generate-target-specs/src/main.rs b/crates/sel4-generate-target-specs/src/main.rs
index 5acb05f85..bc870adb4 100644
--- a/crates/sel4-generate-target-specs/src/main.rs
+++ b/crates/sel4-generate-target-specs/src/main.rs
@@ -223,6 +223,7 @@ impl Context {
 }
 
 fn builtin(triple: &str) -> Target {
+    #[cfg_attr(not(target_spec_has_metadata), allow(unused_mut))]
     let mut target = Target::expect_builtin(&TargetTriple::from_triple(triple));
     #[cfg(target_spec_has_metadata)]
     {