diff --git a/lib/libc/db/db/db.c b/lib/libc/db/db/db.c
--- a/lib/libc/db/db/db.c
+++ b/lib/libc/db/db/db.c
@@ -49,6 +49,12 @@
 #ifndef O_CLOEXEC
 #define O_CLOEXEC 0
 #endif
+#ifndef O_EXLOCK
+#define O_EXLOCK 0
+#endif
+#ifndef O_SHLOCK
+#define O_SHLOCK 0
+#endif
 
 DB *
 dbopen(const char *fname, int flags, int mode, DBTYPE type, const void *openinfo)
diff --git a/tools/build/cross-build/include/linux/fcntl.h b/tools/build/cross-build/include/linux/fcntl.h
--- a/tools/build/cross-build/include/linux/fcntl.h
+++ b/tools/build/cross-build/include/linux/fcntl.h
@@ -1,7 +1,7 @@
 /*-
  * SPDX-License-Identifier: BSD-2-Clause
  *
- * Copyright 2018-2020 Alex Richardson <arichardson@FreeBSD.org>
+ * Copyright 2018-2021 Alex Richardson <arichardson@FreeBSD.org>
  *
  * This software was developed by SRI International and the University of
  * Cambridge Computer Laboratory (Department of Computer Science and
@@ -12,6 +12,9 @@
  * Cambridge Computer Laboratory under DARPA/AFRL contract (FA8750-10-C-0237)
  * ("CTSRD"), as part of the DARPA CRASH research programme.
  *
+ * This work was supported by Innovate UK project 105694, "Digital Security by
+ * Design (DSbD) Technology Platform Prototype".
+ *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
@@ -37,29 +40,9 @@
  */
 #pragma once
 
-
 /* <bits/fcntl.h> includes <bits/stat.h> which contains a member __unused */
 #include "__unused_workaround_start.h"
 #include_next <fcntl.h>
 #include "__unused_workaround_end.h"
 
-#ifdef __unused_undefd
-#undef __unused_undefd
-#define __unused __attribute__((unused))
-#endif
-
 #include <sys/file.h>
-
-#ifndef O_EXLOCK
-#define O_EXLOCK (1 << 30)
-#endif
-#ifndef O_SHLOCK
-#define O_SHLOCK (1 << 31)
-#endif
-
-#undef open
-#define open(path, flags, ...) ({ \
-    int __fd = (open)(path, flags, ##__VA_ARGS__); \
-    if (flags & O_EXLOCK) flock(__fd, LOCK_EX); \
-    if (flags & O_SHLOCK) flock(__fd, LOCK_SH); \
-    __fd; })