diff --git a/library/std/src/sys/unix/os.rs b/library/std/src/sys/unix/os.rs
index 7686b61b67a89..e48b589f7d8f5 100644
--- a/library/std/src/sys/unix/os.rs
+++ b/library/std/src/sys/unix/os.rs
@@ -97,6 +97,7 @@ pub fn errno() -> i32 {
 }
 
 #[cfg(target_os = "dragonfly")]
+#[allow(dead_code)]
 pub fn set_errno(e: i32) {
     extern "C" {
         #[thread_local]