diff --git a/src/threads/thread.c b/src/threads/thread.c
index 96d72be..5bca536 100644
--- a/src/threads/thread.c
+++ b/src/threads/thread.c
@@ -72,7 +72,7 @@ void thread_schedule_tail (struct thread *prev);
 static tid_t allocate_tid (void);
 static bool priority_more (const struct list_elem *a_,
                            const struct list_elem *b_,
-                           void *aux UNUSED)
+                           void *aux UNUSED);
 
 /* Initializes the threading system by transforming the code
    that's currently running into a thread.  This can't work in