diff --git a/tools/build/test-includes/Makefile b/tools/build/test-includes/Makefile
index 3ae39a2cb61f..707ab6f4ca47 100644
--- a/tools/build/test-includes/Makefile
+++ b/tools/build/test-includes/Makefile
@@ -1,54 +1,54 @@
 #
 # A number of header files in sys/* have, going back to 7th Edition Unix in
 # 1979, reqiured other files (like sys/types.h) to compile. Likewise the 4BSD
 # networking code has had prerequisites. However, going back to around the turn
 # of the century, other systems have made them be independently includable
 # (wide-spread header include protection post-dates 7th edition Unix by maybe 4
 # or 5 years judging from netnews sources). Start down the path of making them
 # all independently includable by creating this test that fails buildworld when
 # they are not.
 #
 # The _foo.h files are excluded as they are internal-only headers and/or have
 # special requirements. Since the purpose of this is to allow autoconfig
 # programs to detect FreeBSD has different headers, omitting internal
 # headers cuts down on the noise w/o causing problems for the goal.
 #
 LIB=	test-includes
 INTERNALLIB=	This is a compile-only test
 MAN=
 HDRS!=	(cd ${SRCTOP}/sys; ls sys/[^_]*.h | sort ; ls net*/[^_]*.h | sort)
 NO_PIC=	yes
 
 # Some files have to be clean for extra defines too...
 CFLAGS.event.c=	-D_WANT_KEVENT32 -D_WANT_FREEBSD11_KEVENT
 
 .include "badfiles.inc"
 
-.for h in ${HDRS}
+.for h c in ${HDRS:@x@$x ${x:S,/,_,g:R}.c@}
 .if !${BADHDRS:M${h}}
-SRCS+=	${h:R}.c
-CLEANFILES+=${h:R}.c
-${h:R}.c:
+SRCS+= $c
+CLEANFILES+=$c
+$c:
 	echo "#include <$h>" > ${.TARGET}
 .endif
 .endfor
 
 test-includes: lib${LIB}.a .PHONY
 
 #
 # Target to make the current known bad list. In general, this list should only
 # ever shrink and never grow.
 #
 .PHONY:	badfiles.inc
 badfiles.inc:
 	@(cd ${SRCTOP}/sys;							\
 	echo "# DO NOT EDIT-- this file is automatically @""generated.";	\
 	echo "BADHDRS= \\";							\
 	for i in ${HDRS}; do						\
 		echo "#include <$$i>" |						\
 			${CC} ${CFLAGS} -xc - -c -o /dev/null 2> /dev/null ||	\
 			echo "	$$i \\";					\
 	done;									\
 	echo) > ${.CURDIR}/badfiles.inc
 
 .include <bsd.lib.mk>