diff --git a/tools/build/cross-build/include/common/sys/types.h b/tools/build/cross-build/include/common/sys/types.h
index 82436e7e9224..0bfe2bac2aea 100644
--- a/tools/build/cross-build/include/common/sys/types.h
+++ b/tools/build/cross-build/include/common/sys/types.h
@@ -1,75 +1,83 @@
 /*-
  * SPDX-License-Identifier: BSD-2-Clause
  *
  * Copyright 2018-2020 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.
  *
  * 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.
  *
  * $FreeBSD$
  */
 #pragma once
 #include_next <sys/types.h>
 #include <sys/_types.h>
 /*
  * elftoolchain includes sys/elf32.h which expects that uint32_t is defined
  * However, it only includes <sys/types.h> and not <stdint.h>
  */
 #include <stdint.h>
 
 #if __has_include(<sys/sysmacros.h>)
 /* GLibc defines makedev/minor/major in sysmacros.h instead of sys/types.h */
 #include <sys/sysmacros.h>
 #endif
 
 typedef __UINTPTR_TYPE__ __uintptr_t;
 typedef __INTPTR_TYPE__ __intptr_t;
 
 /* needed for gencat */
 typedef int __nl_item;
 
 typedef size_t u_register_t;
 
 /* capsicum compat: */
 #ifndef _CAP_IOCTL_T_DECLARED
 #define _CAP_IOCTL_T_DECLARED
 typedef unsigned long cap_ioctl_t;
 #endif
 
 #ifndef _CAP_RIGHTS_T_DECLARED
 #define _CAP_RIGHTS_T_DECLARED
 struct cap_rights;
 
 typedef struct cap_rights cap_rights_t;
 
+/*
+ * make.py uses these headers during the bmake bootstrap on Linux only, at
+ * which point sys/bitcount.h won't yet exist, so don't include it there.
+ *
+ * TODO: Untangle this mess.
+ */
+#if __has_include(<sys/bitcount.h>)
 /* Needed for bitstring */
 #include <sys/bitcount.h>
+#endif
 
 #endif