diff --git a/src/unix/linux_like/linux/mod.rs b/src/unix/linux_like/linux/mod.rs
index ae975f1dc629f..291fe5f40c744 100644
--- a/src/unix/linux_like/linux/mod.rs
+++ b/src/unix/linux_like/linux/mod.rs
@@ -3395,7 +3395,7 @@ extern "C" {
     pub fn fanotify_mark(
         fd: ::c_int,
         flags: ::c_uint,
-        mask: u64,
+        mask: ::c_ulonglong,
         dirfd: ::c_int,
         path: *const ::c_char,
     ) -> ::c_int;