Index: Makefile.inc1
===================================================================
--- Makefile.inc1
+++ Makefile.inc1
@@ -1517,7 +1517,8 @@
 .if make(distribution)
 	${_+_}cd ${.CURDIR}; ${CROSSENV} PATH=${TMPPATH} \
 		${MAKE} -f Makefile.inc1 ${IMAKE_INSTALL} \
-		METALOG=${METALOG} MK_TESTS=no installconfig
+		METALOG=${METALOG} MK_TESTS=no \
+		MK_TESTS_SUPPORT=${MK_TESTS_SUPPORT} installconfig
 .endif
 
 #