diff --git a/server/mutex.c b/server/mutex.c
index 1ce86f9..c818d8a 100644
--- a/server/mutex.c
+++ b/server/mutex.c
@@ -32,17 +32,19 @@
 
 static const struct object_ops mutex_ops =
 {
-    sizeof(struct mutex),
-    mutex_dump,
-    add_queue,
-    remove_queue,
-    mutex_signaled,
-    mutex_satisfied,
-    no_read_fd,
-    no_write_fd,
-    no_flush,
-    no_get_file_info,
-    mutex_destroy
+    sizeof(struct mutex),      /* size */
+    mutex_dump,                /* dump */
+    add_queue,                 /* add_queue */
+    remove_queue,              /* remove_queue */
+    mutex_signaled,            /* signaled */
+    mutex_satisfied,           /* satisfied */
+    NULL,                      /* get_poll_events */
+    NULL,                      /* poll_event */
+    no_read_fd,                /* get_read_fd */
+    no_write_fd,               /* get_write_fd */
+    no_flush,                  /* flush */
+    no_get_file_info,          /* get_file_info */
+    mutex_destroy              /* destroy */
 };