diff --git a/Makefile b/Makefile
index 2643d18..673290d 100644
--- a/Makefile
+++ b/Makefile
@@ -1821,7 +1821,8 @@
 quiet_cmd_gen_envp = ENVP    $@
       cmd_gen_envp = \
 	if [ -s "$(ENV_FILE)" ]; then \
-		$(CPP) -P $(CFLAGS) -x assembler-with-cpp -D__ASSEMBLY__ \
+		$(CPP) -P $(CFLAGS) -x assembler-with-cpp -undef \
+			-D__ASSEMBLY__ \
 			-D__UBOOT_CONFIG__ \
 			-I . -I include -I $(srctree)/include \
 			-include linux/kconfig.h -include include/config.h \