diff --git a/releng/releng_build_isojigdo b/releng/releng_build_isojigdo
index 86da7878..105f643b 100755
--- a/releng/releng_build_isojigdo
+++ b/releng/releng_build_isojigdo
@@ -132,8 +132,17 @@ jigit-mkimage \
    -m Debian=${DIR} \
    -o ${IMG}.new
 
-# diff'em TODO: trap the exit code of diff and let the Universe explode
+# trap the exit code of diff and let the Universe explode
 diff ${IMG}.iso ${IMG}.new
+DIFF_RET="$?"
+case ${DIFF_RET} in
+     0)
+      echo -e "$0: diff ${IMG}.iso ${IMG}.new matched.\n"
+     ;;
+     *)
+      echo -e "$0: ATTN: diff returned code: $DIFF_RET\n"
+     ;;
+esac
 
 # sort out the cruft
 if [ ${CLEAN} -eq 1 ]; then
@@ -147,6 +156,7 @@ fi
 printf "\n$0: HINT: manual checks remained to be done:\n"
 printf " * ${IMG}.img boots from USB stick and/or optical media.\n"
 printf " * appended FAT partition is mountable.\n"
+printf " * xorriso -indev ${IMG}.iso -pvd_info\n"
 printf " * fdisk -lu ${IMG}.iso\n"
 
 }