diff --git a/tools/Makefile b/tools/Makefile
index bae3f95c49..9517f203fd 100644
--- a/tools/Makefile
+++ b/tools/Makefile
@@ -169,7 +169,7 @@ HOST_EXTRACFLAGS	+= -DCONFIG_FIT_SIGNATURE_MAX_SIZE=0xffffffff
 HOST_EXTRACFLAGS	+= -DCONFIG_FIT_CIPHER
 endif
 
-ifdef CONFIG_SYS_U_BOOT_OFFS
+ifneq ($(CONFIG_SYS_U_BOOT_OFFS),)
 HOSTCFLAGS_kwbimage.o += -DCONFIG_SYS_U_BOOT_OFFS=$(CONFIG_SYS_U_BOOT_OFFS)
 endif