diff --git a/tools/Makefile b/tools/Makefile
index 5dd33ed..0c3341e 100644
--- a/tools/Makefile
+++ b/tools/Makefile
@@ -133,6 +133,7 @@
 # This affects include/image.h, but including the board config file
 # is tricky, so manually define this options here.
 HOST_EXTRACFLAGS	+= -DCONFIG_FIT_SIGNATURE
+HOST_EXTRACFLAGS	+= -DCONFIG_FIT_SIGNATURE_MAX_SIZE=$(CONFIG_FIT_SIGNATURE_MAX_SIZE)
 endif
 
 ifdef CONFIG_SYS_U_BOOT_OFFS