Index: share/mk/src.sys.obj.mk
===================================================================
--- share/mk/src.sys.obj.mk
+++ share/mk/src.sys.obj.mk
@@ -95,6 +95,8 @@
 # TARGET.TARGET_ARCH handled in OBJROOT already.
 OBJTOP:=	${OBJROOT:H}
 .endif	# ${MK_UNIFIED_OBJDIR} == "yes"
+# Must export since OBJDIR will dynamically be based on it
+.export OBJTOP
 .endif	# empty(OBJTOP)
 
 # Fixup OBJROOT/OBJTOP if using MAKEOBJDIRPREFIX.