diff --git a/tools/build/cross-build/include/linux/fcntl.h b/tools/build/cross-build/include/linux/fcntl.h
index aafcfe43a325..e5718ce5e3ed 100644
--- a/tools/build/cross-build/include/linux/fcntl.h
+++ b/tools/build/cross-build/include/linux/fcntl.h
@@ -1,46 +1,53 @@
 /*-
  * SPDX-License-Identifier: BSD-2-Clause
  *
  * 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
  * Technology) under DARPA contract HR0011-18-C-0016 ("ECATS"), as part of the
  * DARPA SSITH research programme.
  *
  * This software was developed by SRI International and the University of
  * 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:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
  *
  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  */
 #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"
 
 #include <sys/file.h>
+
+/*
+ * On FreeBSD fcntl.h indirectly brings in cdefs.h. On Linux with musl, it does
+ * not. It's needed in our fcntl.h for the cross build since we use
+ * __BEGIN_DECLS and __END_DECLS from it there.
+ */
+#include <sys/cdefs.h>
diff --git a/tools/build/fcntl.h b/tools/build/fcntl.h
index f59f5f7fb20a..6aaf3eef2804 100644
--- a/tools/build/fcntl.h
+++ b/tools/build/fcntl.h
@@ -1,53 +1,46 @@
 /*-
  * Copyright (c) 2016 Jilles Tjoelker <jilles@FreeBSD.org>
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
  *
  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  */
 
 #ifndef _LEGACY_SYS_FCNTL_H_
 #define	_LEGACY_SYS_FCNTL_H_
 
 #include_next <fcntl.h>
 
-/*
- * On FreeBSD fcntl.h indirectly brings in cdefs.h. On Linux with musl, it does
- * not. Unconditionally inlude it here since there's no harm in including it
- * multiple times since we use __BEGIN_DECLS and __END_DECLS from it below.
- */
-#include <sys/cdefs.h>
-
 struct spacectl_range {
 	off_t	r_offset;
 	off_t	r_len;
 };
 
 #define SPACECTL_DEALLOC	1
 
 #define SPACECTL_F_SUPPORTED	0
 
 __BEGIN_DECLS
 int	fspacectl(int, int, const struct spacectl_range *, int,
 	    struct spacectl_range *);
 __END_DECLS
 
 #endif /* !_LEGACY_SYS_STAT_H_ */