diff --git a/test/clock_cast_test/local_t.pass.cpp b/test/clock_cast_test/local_t.pass.cpp
index b6a33bb..b1bb65e 100644
--- a/test/clock_cast_test/local_t.pass.cpp
+++ b/test/clock_cast_test/local_t.pass.cpp
@@ -29,7 +29,6 @@ main()
      assert(st.time_since_epoch() == seconds(946684800));
    }
 
-
    /// utc epoch 
    {
      auto lu = local_days{1970_y/01/01_d};
@@ -38,6 +37,14 @@ main()
      assert(ut.time_since_epoch() == seconds(0));
    }
 
+   // utc leap second
+   {
+     auto lu = local_days{2015_y/07/01_d} - milliseconds(1);
+     auto ut = clock_cast<utc_clock>(lu) + milliseconds(50); //into leap second
+
+     assert(clock_cast<local_t>(ut) == lu);
+   }
+
    /// utc paper example 
    {
      auto lu = local_days{2000_y/01/01_d};