diff --git a/Objects/weakrefobject.c b/Objects/weakrefobject.c
index d12db91..da05950 100644
--- a/Objects/weakrefobject.c
+++ b/Objects/weakrefobject.c
@@ -24,6 +24,8 @@
 {
     self->hash = -1;
     self->wr_object = ob;
+    self->wr_prev = NULL;
+    self->wr_next = NULL;
     Py_XINCREF(callback);
     self->wr_callback = callback;
 }