diff --git a/t/web-lib-funcs-strings.t b/t/web-lib-funcs-strings.t
index 6f3adb238..6e48c8371 100644
--- a/t/web-lib-funcs-strings.t
+++ b/t/web-lib-funcs-strings.t
@@ -38,6 +38,9 @@ subtest 'html_escape' => sub {
 	is(main::html_escape('&'),    '&', 'default mode double-escapes &');
 	is(main::html_escape('&', 1), '&',     'nodblamp preserves existing &');
 	is(main::html_escape('A', 1), 'A',     'nodblamp preserves numeric entity');
+	is(main::html_escape('◦', 1), '◦', 'nodblamp preserves hex numeric entity');
+	is(main::html_escape('◦', 1), '◦', 'nodblamp preserves uppercase hex numeric entity');
+	is(main::html_escape('&#xZZ;', 1), '&#xZZ;', 'nodblamp escapes invalid hex numeric entity');
 	# Note: nodblamp's lookahead matches any &<letters>; as an entity, so
 	# made-up names like &x; are treated as entities and not re-escaped.
 	is(main::html_escape('&x;',   1), '&x;',       'nodblamp preserves arbitrary &word; shape');