diff --git a/ioengine.h b/ioengine.h
index d5a0dc9..7299636 100644
--- a/ioengine.h
+++ b/ioengine.h
@@ -185,8 +185,8 @@
 extern void put_io_u(struct thread_data *, struct io_u *);
 extern void clear_io_u(struct thread_data *, struct io_u *);
 extern void requeue_io_u(struct thread_data *, struct io_u **);
-extern int __must_check io_u_sync_complete(struct thread_data *, struct io_u *, unsigned long *);
-extern int __must_check io_u_queued_complete(struct thread_data *, int, unsigned long *);
+extern int __must_check io_u_sync_complete(struct thread_data *, struct io_u *, uint64_t *);
+extern int __must_check io_u_queued_complete(struct thread_data *, int, uint64_t *);
 extern void io_u_queued(struct thread_data *, struct io_u *);
 extern void io_u_log_error(struct thread_data *, struct io_u *);
 extern void io_u_mark_depth(struct thread_data *, unsigned int);