diff --git a/scheduler/semaphore.c b/scheduler/semaphore.c
index 19160fd..361bf1f 100644
--- a/scheduler/semaphore.c
+++ b/scheduler/semaphore.c
@@ -32,6 +32,8 @@
     SEMAPHORE_Satisfied,   /* satisfied */
     SEMAPHORE_AddWait,     /* add_wait */
     SEMAPHORE_RemoveWait,  /* remove_wait */
+    NULL,                  /* read */
+    NULL,                  /* write */
     SEMAPHORE_Destroy      /* destroy */
 };