Index: /trunk/src/VBox/HostDrivers/Support/linux/Makefile
===================================================================
--- /trunk/src/VBox/HostDrivers/Support/linux/Makefile	(revision 341)
+++ /trunk/src/VBox/HostDrivers/Support/linux/Makefile	(revision 342)
@@ -25,5 +25,5 @@
 # (We have to support basic cross building (ARCH=i386|x86_64).)
 #
-ifeq ($(filter amd64 x86,$(BUILD_TARGET_ARCH)),)
+ifneq ($(filter-out amd64 x86,$(BUILD_TARGET_ARCH)),)
  $(warning Ignoring unknown BUILD_TARGET_ARCH value '$(BUILD_TARGET_ARCH)'.)
  BUILD_TARGET_ARCH :=