use \gdef where submitted as using it

unicodedomino.sty

@@ -28,7 +28,7 @@
 % makes all UTF-8 available in listings.
 
 \NeedsTeXFormat{LaTeX2e}%
-\ProvidesPackage{unicodedomino}[2018/08/05 1.4 Domino for unknown codepoints]%
+\ProvidesPackage{unicodedomino}[2018/08/06 1.5~ Domino for unknown codepoints]%
 \makeatletter%
 
 \ifx\numexpr\@undefined%

unicodedomino_kernel_cosmetics.def

@@ -25,7 +25,7 @@
 %: https://github.com/latex3/latex2e/pull/62
 \ifx\UTFviii@hexbyte\@undefined%
  % format a number as two-digit hex
- \def\UTFviii@hexbyte#1{%
+ \gdef\UTFviii@hexbyte#1{%
   \ifnum#1<16 0\fi%
   \UTFviii@hexnumber{#1}%
  }%
@@ -40,7 +40,7 @@
 %: https://github.com/latex3/latex2e/pull/63
 \ifx\UTFviii@hexcodepoint\@undefined%
  % format a number as Unicode codepoint hex
- \def\UTFviii@hexcodepoint#1{%
+ \gdef\UTFviii@hexcodepoint#1{%
   \ifnum#1<16 U+000%
   \else\ifnum#1<256 U+00%
   \else\ifnum#1<4096 U+0%