diff --git a/c_gen/templates/loci_show.h b/c_gen/templates/loci_show.h
index a66c321..8241f3e 100644
--- a/c_gen/templates/loci_show.h
+++ b/c_gen/templates/loci_show.h
@@ -164,6 +164,8 @@
 
 #define LOCI_SHOW_bitmap_128(writer, cookie, val) writer(cookie, "%" PRIx64 "%" PRIx64, (val).hi, (val).lo)
 
+#define LOCI_SHOW_checksum_128(writer, cookie, val) writer(cookie, "%016" PRIx64 "%016" PRIx64, (val).hi, (val).lo)
+
 /**
  * Generic version for any object
  */