diff --git a/drivers/acpi/acpica/Makefile b/drivers/acpi/acpica/Makefile
index 32d93edbc47914d56a0609c6dbf05f4f87337964..dea65306b68719a1c4e5fd737835ef1819b90107 100644
--- a/drivers/acpi/acpica/Makefile
+++ b/drivers/acpi/acpica/Makefile
@@ -2,7 +2,7 @@
 # Makefile for ACPICA Core interpreter
 #
 
-ccflags-y			:= -Os -DBUILDING_ACPICA
+ccflags-y			:= -Os -D_LINUX -DBUILDING_ACPICA
 ccflags-$(CONFIG_ACPI_DEBUG)	+= -DACPI_DEBUG_OUTPUT
 
 # use acpi.o to put all files here into acpi.o modparam namespace