diff --git a/test/chrono-test.cc b/test/chrono-test.cc
index a2a84ca9..8aef4a32 100644
--- a/test/chrono-test.cc
+++ b/test/chrono-test.cc
@@ -63,8 +63,13 @@ TEST(chrono_test, format_tm) {
   // Short year
   tm.tm_year = 999 - 1900;
   EXPECT_EQ(fmt::format("{:%Y}", tm), "0999");
+  EXPECT_EQ(fmt::format("{:%C%y}", tm), "0999");
   EXPECT_EQ(fmt::format("{:%G}", tm), "0998");
 
+  tm.tm_year = 27 - 1900;
+  EXPECT_EQ(fmt::format("{:%Y}", tm), "0027");
+  EXPECT_EQ(fmt::format("{:%C%y}", tm), "0027");
+
   // for week on the year
   // https://www.cl.cam.ac.uk/~mgk25/iso-time.html
   std::vector<std::string> str_tm_list = {