+_VERS := $(patsubst acpica-unix-%.tar.gz,%,$(wildcard acpica-unix-*.tar.gz))
+_VERS := $(sort $(_VERS))
+_LATEST := $(lastword $(_VERS))
+
+ifeq ($(ACPICAVER),)
+ ifeq ($(_LATEST),)
+ $(error No ACPICA archive found (acpica-unix-%.tar.gz))
+ endif
+
+ ifneq ($(_LATEST),$(_VERS))
+ $(warning Multiple archvies found, picked $(_LATEST))
+ endif
+ ACPICAVER := $(_LATEST)
+endif
+