diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile
index 7beb4e1a9..b697f0051 100644
--- a/drivers/acpi/Makefile
+++ b/drivers/acpi/Makefile
@@ -140,7 +140,7 @@ SRCS+=${ACPICA_SRCS}
 DPADD+=	${LIBDRIVER} ${LIBSYS}
 LDADD+=	-ldriver -lsys
 
-CFLAGS += -I./include
+CPPFLAGS += -I${.CURDIR}/include
 CFLAGS += -DACPI_LIBRARY
 CFLAGS += -std=c99