diff --git a/tests/test-locale-gen.sh b/tests/test-locale-gen.sh
index 5d7c1384abf18a19d96dfdb58dd52472c76c4f5b..81b6b948cb676c0ae2ec4128a16189176592002f 100755
--- a/tests/test-locale-gen.sh
+++ b/tests/test-locale-gen.sh
@@ -129,7 +129,7 @@ else
     # shellcheck disable=SC2030
     (
         cd "$tmpdir/1"
-        export LC_CTYPE=cy_GB.UTF-8
+        export LC_CTYPE=cy_GB.utf8
         export LC_COLLATE=cs_CZ
         export LC_IDENTIFICATION=it_IT@euro
         export LC_MEASUREMENT=mn_MN
@@ -158,6 +158,7 @@ else
     for locale in \
         cs_CZ \
         cy_GB.UTF-8 \
+        cy_GB.utf8 \
         en_AU.UTF-8 \
         en_DK \
         en_GB.ISO-8859-15 \