diff --git a/src/libstd/sys/unix/c.rs b/src/libstd/sys/unix/c.rs
index a4ebcbd25d00e..208dc60e405dc 100644
--- a/src/libstd/sys/unix/c.rs
+++ b/src/libstd/sys/unix/c.rs
@@ -214,8 +214,8 @@ mod signal {
         sa_resv: [libc::c_int, ..1],
     }
 
-    impl ::kinds::Send for sigaction { }
-    impl ::kinds::Sync for sigaction { }
+    unsafe impl ::kinds::Send for sigaction { }
+    unsafe impl ::kinds::Sync for sigaction { }
 
     #[repr(C)]
     pub struct sigset_t {