diff --git a/drivers/bios_emulator/Makefile b/drivers/bios_emulator/Makefile
index dd9c102..feba4da 100644
--- a/drivers/bios_emulator/Makefile
+++ b/drivers/bios_emulator/Makefile
@@ -23,6 +23,7 @@
 
 CFLAGS += $(EXTRA_CFLAGS)
 HOSTCFLAGS += $(EXTRA_CFLAGS)
+CPPFLAGS += $(EXTRA_CFLAGS)
 
 all:	$(LIB)