diff --git a/lib/time.rb b/lib/time.rb
index 4d1a027..8fff3b1 100644
--- a/lib/time.rb
+++ b/lib/time.rb
@@ -670,7 +670,9 @@ def rfc3339(time)
     if RUBY_VERSION >= "3.2"
       def _xmlschema(pattern, time) # :nodoc:
         if pattern.match?(time)
-          new(time.strip)
+          time = time.strip
+          time.upcase!
+          new(time)
         else
           raise ArgumentError.new("invalid xmlschema format: #{time.inspect}")
         end
diff --git a/test/test_time.rb b/test/test_time.rb
index ac7a5b6..f23e8cd 100644
--- a/test/test_time.rb
+++ b/test/test_time.rb
@@ -162,6 +162,8 @@ def subtest_xmlschema(method)
                  Time.__send__(method, "2000-03-04T23:00:00+03:00"))
     assert_equal(Time.utc(2000, 3, 4, 20, 0, 0),
                  Time.__send__(method, "2000-03-04T20:00:00Z"))
+    assert_equal(Time.utc(2000, 3, 4, 20, 0, 0),
+                 Time.__send__(method, "2000-03-04t20:00:00z"))
     assert_equal(Time.utc(2000, 1, 16, 12, 0, 0),
                  Time.__send__(method, "2000-01-16T12:00:00Z"))
     assert_equal(Time.utc(1999, 12, 31, 23, 0, 0),