diff --git a/test/message/append.cpp b/test/message/append.cpp
index c6eb152..288199b 100644
--- a/test/message/append.cpp
+++ b/test/message/append.cpp
@@ -9,6 +9,7 @@
 #include <string>
 #include <tuple>
 #include <unordered_map>
+#include <unordered_set>
 #include <variant>
 #include <vector>
 
@@ -257,6 +258,22 @@
     new_message().append(s);
 }
 
+TEST_F(AppendTest, UnorderedSet)
+{
+    const std::unordered_set<std::string> s{"one", "two", "eight"};
+
+    {
+        testing::InSequence seq;
+        expect_open_container(SD_BUS_TYPE_ARRAY, "s");
+        for (const auto& i : s)
+        {
+            expect_basic_string(SD_BUS_TYPE_STRING, i.c_str());
+        }
+        expect_close_container();
+    }
+    new_message().append(s);
+}
+
 TEST_F(AppendTest, Map)
 {
     const std::map<int, std::string> m{