diff --git a/src/test/test-unit-name.c b/src/test/test-unit-name.c
index 24436cab0b..986fcbb1af 100644
--- a/src/test/test-unit-name.c
+++ b/src/test/test-unit-name.c
@@ -73,6 +73,12 @@ static void test_unit_name_is_valid(void) {
         test_unit_name_is_valid_one("user@1000.slice", UNIT_NAME_ANY, true);
         test_unit_name_is_valid_one("user@1000.slice", UNIT_NAME_INSTANCE, true);
         test_unit_name_is_valid_one("user@1000.slice", UNIT_NAME_TEMPLATE, false);
+
+        test_unit_name_is_valid_one("foo@%i.service", UNIT_NAME_ANY, false);
+        test_unit_name_is_valid_one("foo@%i.service", UNIT_NAME_INSTANCE, false);
+        test_unit_name_is_valid_one("foo@%%i.service", UNIT_NAME_INSTANCE, false);
+        test_unit_name_is_valid_one("foo@%%i%f.service", UNIT_NAME_INSTANCE, false);
+        test_unit_name_is_valid_one("foo@%F.service", UNIT_NAME_INSTANCE, false);
 }
 
 static void test_unit_name_replace_instance_one(const char *pattern, const char *repl, const char *expected, int ret) {