diff --git a/ChangeLog b/ChangeLog
index 50c932396e..a5c5e8bf8d 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+Tue Feb 28 17:16:01 2012  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* lib/time.rb (Time#xmlschema): use strftime specifiers instead of
+	  fractional exponential calcuation which yields undesirable
+	  result.  [ruby-core:42997][Bug #6100]
+
 Tue Feb 28 14:15:29 2012  Eric Hodel  <drbrain@segment7.net>
 
 	* lib/net/protocol.rb: Add OpenTimeout subclass of Timeout::Error
diff --git a/lib/time.rb b/lib/time.rb
index c8aa3b12b2..977010087e 100644
--- a/lib/time.rb
+++ b/lib/time.rb
@@ -620,20 +620,12 @@ class Time
   # You must require 'time' to use this method.
   #
   def xmlschema(fraction_digits=0)
-    sprintf('%0*d-%02d-%02dT%02d:%02d:%02d',
-      year < 0 ? 5 : 4, year, mon, day, hour, min, sec) +
-    if fraction_digits <= 0
-      ''
-    else
-      '.' + sprintf('%0*d', fraction_digits, (subsec * 10**fraction_digits).floor)
-    end +
-    if utc?
-      'Z'
-    else
-      off = utc_offset
-      sign = off < 0 ? '-' : '+'
-      sprintf('%s%02d:%02d', sign, *(off.abs / 60).divmod(60))
+    fraction_digits = fraction_digits.to_i
+    s = strftime("%FT%T")
+    if fraction_digits > 0
+      s << strftime(".%#{fraction_digits}N")
     end
+    s << (utc? ? 'Z' : strftime("%:z"))
   end
   alias iso8601 xmlschema
 end
diff --git a/test/test_time.rb b/test/test_time.rb
index 9dbce3f654..0a4e8a70c3 100644
--- a/test/test_time.rb
+++ b/test/test_time.rb
@@ -154,22 +154,28 @@ class TestTimeExtension < Test::Unit::TestCase # :nodoc:
   end
 
   def test_encode_xmlschema
+    bug6100 = '[ruby-core:42997]'
+
     t = Time.utc(2001, 4, 17, 19, 23, 17, 300000)
     assert_equal("2001-04-17T19:23:17Z", t.xmlschema)
     assert_equal("2001-04-17T19:23:17.3Z", t.xmlschema(1))
     assert_equal("2001-04-17T19:23:17.300000Z", t.xmlschema(6))
     assert_equal("2001-04-17T19:23:17.3000000Z", t.xmlschema(7))
+    assert_equal("2001-04-17T19:23:17.3Z", t.xmlschema(1.9), bug6100)
 
     t = Time.utc(2001, 4, 17, 19, 23, 17, 123456)
     assert_equal("2001-04-17T19:23:17.1234560Z", t.xmlschema(7))
     assert_equal("2001-04-17T19:23:17.123456Z", t.xmlschema(6))
     assert_equal("2001-04-17T19:23:17.12345Z", t.xmlschema(5))
     assert_equal("2001-04-17T19:23:17.1Z", t.xmlschema(1))
+    assert_equal("2001-04-17T19:23:17.1Z", t.xmlschema(1.9), bug6100)
 
     t = Time.at(2.quo(3)).getlocal("+09:00")
     assert_equal("1970-01-01T09:00:00.666+09:00", t.xmlschema(3))
     assert_equal("1970-01-01T09:00:00.6666666666+09:00", t.xmlschema(10))
     assert_equal("1970-01-01T09:00:00.66666666666666666666+09:00", t.xmlschema(20))
+    assert_equal("1970-01-01T09:00:00.6+09:00", t.xmlschema(1.1), bug6100)
+    assert_equal("1970-01-01T09:00:00.666+09:00", t.xmlschema(3.2), bug6100)
 
     t = Time.at(123456789.quo(9999999999)).getlocal("+09:00")
     assert_equal("1970-01-01T09:00:00.012+09:00", t.xmlschema(3))
@@ -177,6 +183,7 @@ class TestTimeExtension < Test::Unit::TestCase # :nodoc:
     assert_equal("1970-01-01T09:00:00.0123456789+09:00", t.xmlschema(10))
     assert_equal("1970-01-01T09:00:00.0123456789012345678+09:00", t.xmlschema(19))
     assert_equal("1970-01-01T09:00:00.01234567890123456789+09:00", t.xmlschema(20))
+    assert_equal("1970-01-01T09:00:00.012+09:00", t.xmlschema(3.8), bug6100)
 
     t = Time.utc(1)
     assert_equal("0001-01-01T00:00:00Z", t.xmlschema)