diff --git a/libc/include/sys/epoll.h b/libc/include/sys/epoll.h
index 374573737..302c8c389 100644
--- a/libc/include/sys/epoll.h
+++ b/libc/include/sys/epoll.h
@@ -55,10 +55,10 @@ int epoll_create1(int __flags) __INTRODUCED_IN(21);
 #undef EPOLL_CLOEXEC
 #endif
 
-int epoll_ctl(int __epoll_fd, int __op, int __fd, struct epoll_event* __event);
-int epoll_wait(int __epoll_fd, struct epoll_event* __events, int __event_count, int __timeout_ms);
-int epoll_pwait(int __epoll_fd, struct epoll_event* __events, int __event_count, int __timeout_ms, const sigset_t* __mask) __INTRODUCED_IN(21);
-int epoll_pwait64(int __epoll_fd, struct epoll_event* __events, int __event_count, int __timeout_ms, const sigset64_t* __mask) __INTRODUCED_IN(28);
+int epoll_ctl(int __epoll_fd, int __op, int __fd, struct epoll_event* __BIONIC_COMPLICATED_NULLNESS __event);
+int epoll_wait(int __epoll_fd, struct epoll_event* _Nonnull __events, int __event_count, int __timeout_ms);
+int epoll_pwait(int __epoll_fd, struct epoll_event* _Nonnull __events, int __event_count, int __timeout_ms, const sigset_t* _Nullable __mask) __INTRODUCED_IN(21);
+int epoll_pwait64(int __epoll_fd, struct epoll_event* _Nonnull __events, int __event_count, int __timeout_ms, const sigset64_t* _Nullable __mask) __INTRODUCED_IN(28);
 
 __END_DECLS