diff --git a/libc/kernel/uapi/linux/in.h b/libc/kernel/uapi/linux/in.h
index 53d3074..3947d5a 100644
--- a/libc/kernel/uapi/linux/in.h
+++ b/libc/kernel/uapi/linux/in.h
@@ -141,6 +141,7 @@
 #define MCAST_MSFILTER 48
 #define IP_MULTICAST_ALL 49
 #define IP_UNICAST_IF 50
+#define IP_LOCAL_PORT_RANGE 51
 #define MCAST_EXCLUDE 0
 #define MCAST_INCLUDE 1
 #define IP_DEFAULT_MULTICAST_TTL 1