diff --git a/lib/checksum.h b/lib/checksum.h
index da1d3cb..b310f74 100644
--- a/lib/checksum.h
+++ b/lib/checksum.h
@@ -1,2 +1,3 @@
 extern int in_cksum(void *, int);
+#define FLETCHER_CHECKSUM_VALIDATE 0xffff
 extern u_int16_t fletcher_checksum(u_char *, const size_t len, const uint16_t offset);