diff --git a/libc/kernel/uapi/linux/pidfd.h b/libc/kernel/uapi/linux/pidfd.h
index 9a49e6a..082b4a0 100644
--- a/libc/kernel/uapi/linux/pidfd.h
+++ b/libc/kernel/uapi/linux/pidfd.h
@@ -9,4 +9,8 @@
 #include <linux/types.h>
 #include <linux/fcntl.h>
 #define PIDFD_NONBLOCK O_NONBLOCK
+#define PIDFD_THREAD O_EXCL
+#define PIDFD_SIGNAL_THREAD (1UL << 0)
+#define PIDFD_SIGNAL_THREAD_GROUP (1UL << 1)
+#define PIDFD_SIGNAL_PROCESS_GROUP (1UL << 2)
 #endif