diff --git a/ext/socket/mkconstants.rb b/ext/socket/mkconstants.rb
index 655e990e3d..5bedbac5ac 100644
--- a/ext/socket/mkconstants.rb
+++ b/ext/socket/mkconstants.rb
@@ -329,6 +329,8 @@ AF_NETGRAPH
 PF_NETGRAPH
 AF_MAX
 PF_MAX
+AF_PACKET
+PF_PACKET
 
 AF_E164
 PF_XTP