diff --git a/test/typescript/custom-types/i18next.d.ts b/test/typescript/custom-types/i18next.d.ts
index 562adbfb..70cb262d 100644
--- a/test/typescript/custom-types/i18next.d.ts
+++ b/test/typescript/custom-types/i18next.d.ts
@@ -8,6 +8,9 @@ declare module 'i18next' {
       custom: {
         foo: 'foo';
         bar: 'bar';
+        baz: {
+          bing: 'boop';
+        };
       };
       alternate: {
         baz: 'baz';
diff --git a/test/typescript/custom-types/t.test.ts b/test/typescript/custom-types/t.test.ts
index 4ea51f7b..48d3bf53 100644
--- a/test/typescript/custom-types/t.test.ts
+++ b/test/typescript/custom-types/t.test.ts
@@ -50,6 +50,8 @@ function i18nextTUsage() {
   i18next.t('bar', { ns: 'alternate' });
   // i18next.t('bar', {}).trim();
   i18next.t('bar').trim();
+  i18next.t('baz.bing').trim();
+  i18next.t('alternate:foobar.barfoo').trim();
 
   i18next.t('custom:bar', { defaultValue: 'some default value' });
   i18next.t('custom:bar', 'some default value');