diff --git a/test/ruby/test_time_tz.rb b/test/ruby/test_time_tz.rb
index 531d76b040..f66cd9bec2 100644
--- a/test/ruby/test_time_tz.rb
+++ b/test/ruby/test_time_tz.rb
@@ -695,6 +695,13 @@ module TestTimeTZ::WithTZ
     assert_equal(t.dst?, t2.dst?)
   end
 
+  def subtest_fractional_second(time_class, tz, tzarg, tzname, abbr, utc_offset)
+    t = time_class.new(2024, 1, 1, 23, 59, 59.9r, tzarg)
+    assert_equal(utc_offset[t.dst? ? 1 : 0], t.utc_offset)
+    t = time_class.new(2024, 7, 1, 23, 59, 59.9r, tzarg)
+    assert_equal(utc_offset[t.dst? ? 1 : 0], t.utc_offset)
+  end
+
   def test_invalid_zone
     make_timezone("INVALID", "INV", 0)
   rescue => e
@@ -719,6 +726,7 @@ module TestTimeTZ::WithTZ
     "Asia/Tokyo" => ["JST", +9*3600],
     "America/Los_Angeles" => ["PST", -8*3600, "PDT", -7*3600],
     "Africa/Ndjamena" => ["WAT", +1*3600],
+    "Etc/UTC" => ["UTC", 0],
   }
 
   def make_timezone(tzname, abbr, utc_offset, abbr2 = nil, utc_offset2 = nil)
diff --git a/time.c b/time.c
index 50bdb2bf6b..7f859d5eb4 100644
--- a/time.c
+++ b/time.c
@@ -2322,7 +2322,7 @@ zone_timelocal(VALUE zone, VALUE time)
     struct time_object *tobj = DATA_PTR(time);
     wideval_t t, s;
 
-    t = rb_time_unmagnify(tobj->timew);
+    split_second(tobj->timew, &t, &s);
     tm = tm_from_time(rb_cTimeTM, time);
     utc = rb_check_funcall(zone, id_local_to_utc, 1, &tm);
     if (UNDEF_P(utc)) return 0;
diff --git a/version.h b/version.h
index c99222f215..58facb62aa 100644
--- a/version.h
+++ b/version.h
@@ -11,7 +11,7 @@
 # define RUBY_VERSION_MINOR RUBY_API_VERSION_MINOR
 #define RUBY_VERSION_TEENY 3
 #define RUBY_RELEASE_DATE RUBY_RELEASE_YEAR_STR"-"RUBY_RELEASE_MONTH_STR"-"RUBY_RELEASE_DAY_STR
-#define RUBY_PATCHLEVEL 166
+#define RUBY_PATCHLEVEL 167
 
 #include "ruby/version.h"
 #include "ruby/internal/abi.h"