diff --git a/unicodedomino_compat.def b/unicodedomino_compat.def
index 1beff1822af6182268e72ef00ad05b7aa62aafe9..a581c2a61a567e5900126404fb09f3996b667095 100644
--- a/unicodedomino_compat.def
+++ b/unicodedomino_compat.def
@@ -20,6 +20,7 @@
 %-
 % Compatibility code with older utf8.def versions
 
+% added in v1.2a 2018/03/24
 \ifx\UTFviii@invalid@help\@undefined%
  \def\UTFviii@invalid@help{%
   Do ensure the source document is saved in UTF-8 encoding%