diff --git a/unix-ffi/socket/manifest.py b/unix-ffi/socket/manifest.py
index a0a384d37..9cb582a84 100644
--- a/unix-ffi/socket/manifest.py
+++ b/unix-ffi/socket/manifest.py
@@ -1,4 +1,4 @@
-metadata(version="0.5.2")
+metadata(version="0.5.3")
 
 # Originally written by Paul Sokolovsky.
 
diff --git a/unix-ffi/socket/socket.py b/unix-ffi/socket/socket.py
index 1b47f9840..16d661b0c 100644
--- a/unix-ffi/socket/socket.py
+++ b/unix-ffi/socket/socket.py
@@ -4,8 +4,6 @@
 
 _GLOBAL_DEFAULT_TIMEOUT = 30
 IPPROTO_IP = 0
-IP_ADD_MEMBERSHIP = 35
-IP_DROP_MEMBERSHIP = 36
 INADDR_ANY = 0
 
 error = OSError