diff --git a/Modules/socketmodule.h b/Modules/socketmodule.h
index 8515499..d98e00e 100644
--- a/Modules/socketmodule.h
+++ b/Modules/socketmodule.h
@@ -132,6 +132,7 @@
                                         sets a Python exception */
     double sock_timeout;                 /* Operation timeout in seconds;
                                         0.0 means non-blocking */
+    PyObject *weakreflist;
 } PySocketSockObject;
 
 /* --- C API ----------------------------------------------------*/