$(foreach tool, $(filter-out xz,$(tools-y)), $(eval $(curdir)/$(tool)/compile += $(curdir)/xz/compile))
-# make any tool depend on tar, xz and patch to ensure that archives can be unpacked and patched properly
-tools-core := tar xz patch
+# make any tool depend on the following to ensure that archives can be unpacked and patched properly
+tools-core += patch
+tools-core += tar
+tools-core += xz
$(foreach tool, $(tools-y), $(eval $(curdir)/$(tool)/compile += $(patsubst %,$(curdir)/%/compile,$(tools-core))))
tools-y += $(tools-core)