diff --git a/perl/t/05_preferred_int.t b/perl/t/05_preferred_int.t
index 9860711..67d11aa 100644
--- a/perl/t/05_preferred_int.t
+++ b/perl/t/05_preferred_int.t
@@ -16,6 +16,7 @@ sub pis ($$) {
     # is(Dumper(Data::MessagePack->unpack(Data::MessagePack->pack($_[0]))), Dumper($_[0]));
 }
 
+my $is_win = $^O eq 'MSWin32';
 my @dat = (
     '',      'a0',
     '0',     '00',
@@ -29,12 +30,16 @@ my @dat = (
     ''.0xFFFFFF => 'ce 00 ff ff ff',
     ''.0xFFFFFFFF => 'ce ff ff ff ff',
     ''.0xFFFFFFFFF => 'ab 36 38 37 31 39 34 37 36 37 33 35',
-    ''.0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFF => 'b4 38 2e 33 30 37 36 37 34 39 37 33 36 35 35 37 32 65 2b 33 34',
+    ''.0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFF => $is_win ?
+                                            'b5 38 2e 33 30 37 36 37 34 39 37 33 36 35 35 37 32 65 2b 30 33 34'
+                                          : 'b4 38 2e 33 30 37 36 37 34 39 37 33 36 35 35 37 32 65 2b 33 34',
     '-'.0x8000000 => 'd2 f8 00 00 00',
     '-'.0x80000000 => 'd2 80 00 00 00',
     '-'.0x800000000 => 'ac 2d 33 34 33 35 39 37 33 38 33 36 38',
     '-'.0x8000000000 => 'ad 2d 35 34 39 37 35 35 38 31 33 38 38 38',
-    '-'.0x800000000000000000000000000000 => 'b5 2d 36 2e 36 34 36 31 33 39 39 37 38 39 32 34 35 38 65 2b 33 35',
+    '-'.0x800000000000000000000000000000 => $is_win ?
+                                            'b6 2d 36 2e 36 34 36 31 33 39 39 37 38 39 32 34 35 38 65 2b 30 33 35'
+                                          : 'b5 2d 36 2e 36 34 36 31 33 39 39 37 38 39 32 34 35 38 65 2b 33 35',
     {'0' => '1'}, '81 00 01',
     {'abc' => '1'}, '81 a3 61 62 63 01',
 );