diff --git a/second/head.h b/second/head.h
index d87e649..c2ff195 100644
--- a/second/head.h
+++ b/second/head.h
@@ -45,10 +45,18 @@ struct emile_l2_header {
 	u_int32_t	gestaltID;
 }  __attribute__((packed));
 
+#define EMILE_ID_MASK		0xFFF0
+#define EMILE_VERSION_MASK	0x000F
+
+#define EMILE_ID(a)		((a) & EMILE_ID_MASK)
+#define EMILE_VERSION(a)	((a) & EMILE_VERSION_MASK)
+
 #define EMILE_01_SIGNATURE	(('E'<<24)|('M'<<16)|('0'<<8)|'1')
 #define EMILE_02_SIGNATURE	(('E'<<24)|('M'<<16)|('0'<<8)|'2')
 #define EMILE_03_SIGNATURE	(('E'<<24)|('M'<<16)|('0'<<8)|'3')
 
+#define EMILE_COMPAT(a,b)	( ( EMILE_ID(a) == EMILE_ID(b) ) && \
+				  ( EMILE_VERSION(a) <= EMILE_VERSION(b) ) )
 enum {
 	STDOUT_VGA	=	0x00000001,
 	STDOUT_SERIAL0	=	0x00000002,
diff --git a/second/main.c b/second/main.c
index 77df962..954a203 100644
--- a/second/main.c
+++ b/second/main.c
@@ -58,7 +58,7 @@ int start(emile_l2_header_t* info)
 	printf("EMILE v"VERSION" (c) 2004 Laurent Vivier\n");
 	printf("This is free software, redistribute it under GPL\n");
 
-	if (info->signature < EMILE_03_SIGNATURE)
+	if (!EMILE_COMPAT(EMILE_03_SIGNATURE, info->signature))
 		error("Bad header signature !\n");
 
 	arch_init();