diff --git a/os.h b/os.h
index 554423f..80c121f 100644
--- a/os.h
+++ b/os.h
@@ -117,3 +117,7 @@ void mutex_acquire(mutex_t *mutex);
  * In addition, calls to acquire/release should be balanced.
  */
 void mutex_release(mutex_t *mutex);
+
+/*
+ * The end of the file.
+ */