diff --git a/src/backend/InvenTree/common/tests.py b/src/backend/InvenTree/common/tests.py
index 2bd0c41db8..de876bc64e 100644
--- a/src/backend/InvenTree/common/tests.py
+++ b/src/backend/InvenTree/common/tests.py
@@ -620,6 +620,26 @@ class GlobalSettingsApiTest(InvenTreeAPITestCase):
 
         self.assertEqual(codes, 'AUD,USD,GBP')
 
+    def test_report_currency_locale(self):
+        """Test validation of the REPORT_CURRENCY_LOCALE setting."""
+        url = reverse(
+            'api-global-setting-detail', kwargs={'key': 'REPORT_CURRENCY_LOCALE'}
+        )
+
+        # Valid locale values are accepted
+        for valid in ['en-us', 'en-gb', 'en-au', 'de-de', 'fr-fr']:
+            response = self.patch(url, data={'value': valid}, expected_code=200)
+            self.assertEqual(response.data['value'], valid)
+
+        # Blank value is accepted (means "use system locale")
+        response = self.patch(url, data={'value': ''}, expected_code=200)
+        self.assertEqual(response.data['value'], '')
+
+        # Invalid locale values are rejected
+        for invalid in ['xx-zz', 'not-a-locale']:
+            response = self.patch(url, data={'value': invalid}, expected_code=400)
+            self.assertIn('Invalid locale value', str(response.data))
+
     def test_company_name(self):
         """Test a settings object lifecycle e2e."""
         setting = InvenTreeSetting.get_setting_object('INVENTREE_COMPANY_NAME')