diff --git a/arch/x86/include/asm/kexec.h b/arch/x86/include/asm/kexec.h
index 3b9d23479eca11497e9b1fbdf80ef84e410766dd..b3a2b4309a31e4ab982b0a9e841c401e8fccb1c7 100644
--- a/arch/x86/include/asm/kexec.h
+++ b/arch/x86/include/asm/kexec.h
@@ -70,7 +70,7 @@ struct kimage;
 
 /* Memory to backup during crash kdump */
 #define KEXEC_BACKUP_SRC_START	(0UL)
-#define KEXEC_BACKUP_SRC_END	(640 * 1024UL)	/* 640K */
+#define KEXEC_BACKUP_SRC_END	(640 * 1024UL - 1)	/* 640K */
 
 /*
  * CPU does not save ss and sp on stack if execution is already