diff --git a/Makefile b/Makefile
index 3b7cc830467f..a984fc6cd5fb 100644
--- a/Makefile
+++ b/Makefile
@@ -248,8 +248,19 @@ tinderbox toolchains kernel-toolchains: .MAKE
 ${TGTS}:
 	${_+_}@cd ${.CURDIR}; ${_MAKE} ${.TARGET}
 
-# Set a reasonable default
+# The historic default "all" target creates files which may cause stale
+# or (in the cross build case) unlinkable results. Fail with an error
+# when no target is given. The users can set ALLOW_IMPLICIT_TARGET or
+# explicitly specify "all" if they want the historic behavior.
+.ifdef ALLOW_IMPLICIT_TARGET
 .MAIN:	all
+.else
+.MAIN:	_guard
+
+_guard:
+	@echo "Use an explicit target or set ALLOW_IMPLICIT_TARGET"
+	@false
+.endif
 
 STARTTIME!= LC_ALL=C date
 CHECK_TIME!= find ${.CURDIR}/sys/sys/param.h -mtime -0s ; echo
diff --git a/lib/libz-cheri/adler32.c b/lib/libz-cheri/adler32.c
index d015b4c55cb7..af960c0e1353 100644
--- a/lib/libz-cheri/adler32.c
+++ b/lib/libz-cheri/adler32.c
@@ -7,6 +7,8 @@
 
 #include "zutil.h"
 
+#include <machine/cherireg.h>
+
 #define local static
 
 local uLong adler32_combine_ OF((uLong adler1, uLong adler2, z_off64_t len2));