diff --git a/Makefile.inc1 b/Makefile.inc1
index 47ed443da959..c9aa141048d8 100644
--- a/Makefile.inc1
+++ b/Makefile.inc1
@@ -569,7 +569,8 @@ _aout_tools=	usr.bin/size usr.bin/strip gnu/usr.bin/as gnu/usr.bin/ld
 
 cross-tools:
 .for _tool in ${_aout_tools} ${_btxld} ${_elf2exe} usr.bin/genassym \
-    usr.bin/gensetdefs gnu/usr.bin/binutils usr.bin/objformat gnu/usr.bin/cc
+    usr.bin/gensetdefs gnu/usr.bin/binutils usr.bin/objformat gnu/usr.bin/cc \
+    usr.sbin/mtree
 	cd ${.CURDIR}/${_tool}; \
 		${MAKE} obj; \
 		${MAKE} depend; \