diff --git a/options.mk b/options.mk
index 2fe2b318..f1557c94 100644
--- a/options.mk
+++ b/options.mk
@@ -58,6 +58,7 @@ ifeq ($(SIGN),ED25519)
   PUBLIC_KEY_OBJS=./src/ed25519_pub_key.o
   CFLAGS+=-D"WOLFBOOT_SIGN_ED25519"
   STACK_USAGE?=1180
+  IMAGE_HEADER_SIZE?=256
 endif
 
 ifeq ($(SIGN),ED448)
@@ -83,14 +84,14 @@ ifeq ($(SIGN),ED448)
   endif
   PUBLIC_KEY_OBJS=./src/ed448_pub_key.o
   CFLAGS+=-D"WOLFBOOT_SIGN_ED448"
-  IMAGE_HEADER_SIZE=512
+  IMAGE_HEADER_SIZE?=512
 endif
 
 ifeq ($(SIGN),RSA2048)
   KEYGEN_OPTIONS+=--rsa2048
   SIGN_OPTIONS+=--rsa2048
   PRIVATE_KEY=rsa2048.der
-  IMAGE_HEADER_SIZE=512
+  IMAGE_HEADER_SIZE?=512
   WOLFCRYPT_OBJS+= \
     $(RSA_EXTRA_OBJS) \
     $(MATH_OBJS) \
@@ -119,7 +120,7 @@ ifeq ($(SIGN),RSA4096)
   KEYGEN_OPTIONS+=--rsa4096
   SIGN_OPTIONS+=--rsa4096
   PRIVATE_KEY=rsa4096.der
-  IMAGE_HEADER_SIZE=1024
+  IMAGE_HEADER_SIZE?=1024
   WOLFCRYPT_OBJS+= \
     $(RSA_EXTRA_OBJS) \
     $(MATH_OBJS) \