diff --git a/src/uptime/uptime.rs b/src/uptime/uptime.rs
index feb151fdd..772b077b4 100644
--- a/src/uptime/uptime.rs
+++ b/src/uptime/uptime.rs
@@ -44,7 +44,7 @@ extern {
     fn endutxent();
 
     #[cfg(target_os = "linux")]
-    #[cfg(target_os = "macs")]
+    #[cfg(target_os = "macos")]
     fn utmpxname(file: *const c_char) -> c_int;
 }