diff --git a/perl/lib/Data/MessagePack.pm b/perl/lib/Data/MessagePack.pm
index afe37af3..4a1da179 100644
--- a/perl/lib/Data/MessagePack.pm
+++ b/perl/lib/Data/MessagePack.pm
@@ -5,6 +5,7 @@ use 5.008001;
 
 our $VERSION = '0.34';
 our $PreferInteger = 0;
+our $Canonical = 0;
 
 sub true () {
     require Data::MessagePack::Boolean;
diff --git a/perl/lib/Data/MessagePack/PP.pm b/perl/lib/Data/MessagePack/PP.pm
index f179ad74..65ce24b4 100644
--- a/perl/lib/Data/MessagePack/PP.pm
+++ b/perl/lib/Data/MessagePack/PP.pm
@@ -182,7 +182,12 @@ sub _pack {
             : $num < 2 ** 32 - 1 ? CORE::pack( 'CN', 0xdf,  $num )
             : _unexpected("number %d", $num)
         ;
-        return join( '', $header, map { _pack( $_ ) } %$value );
+
+        if ($Data::MessagePack::Canonical) {
+            return join( '', $header, map { _pack( $_ ), _pack($value->{$_}) } sort { $a cmp $b } keys %$value );
+        } else {
+            return join( '', $header, map { _pack( $_ ) } %$value );
+        }
     }
 
     elsif ( ref( $value ) eq 'Data::MessagePack::Boolean' ) {
diff --git a/perl/t/17_canonical.t b/perl/t/17_canonical.t
new file mode 100644
index 00000000..5389e2f9
--- /dev/null
+++ b/perl/t/17_canonical.t
@@ -0,0 +1,32 @@
+
+use strict;
+use warnings;
+use Test::More;
+use Data::MessagePack;
+
+$Data::MessagePack::Canonical = 1;
+
+my $data = {
+	'foo' => {
+		'a' => '',
+		'b' => '',
+		'c' => '',
+		'd' => '',
+		'e' => '',
+		'f' => '',
+		'g' => '',
+	}
+};
+
+my $packed1 = +Data::MessagePack->pack($data);
+my $packed2 = +Data::MessagePack->pack(Data::MessagePack->unpack($packed1));
+my $packed3 = +Data::MessagePack->pack(Data::MessagePack->unpack($packed2));
+my $packed4 = +Data::MessagePack->pack(Data::MessagePack->unpack($packed3));
+my $packed5 = +Data::MessagePack->pack(Data::MessagePack->unpack($packed4));
+
+is $packed1, $packed2;
+is $packed1, $packed3;
+is $packed1, $packed4;
+is $packed1, $packed5;
+
+done_testing;
diff --git a/perl/xs-src/pack.c b/perl/xs-src/pack.c
index 862808eb..582b1202 100644
--- a/perl/xs-src/pack.c
+++ b/perl/xs-src/pack.c
@@ -211,9 +211,32 @@ STATIC_INLINE void _msgpack_pack_rv(enc_t *enc, SV* sv, int depth) {
 
         msgpack_pack_map(enc, count);
 
-        while ((he = hv_iternext(hval))) {
-            _msgpack_pack_sv(enc, hv_iterkeysv(he), depth);
-            _msgpack_pack_sv(enc, HeVAL(he), depth);
+        if (SvTRUE(get_sv("Data::MessagePack::Canonical", 0))) {
+            AV* keys = newAV();
+            av_extend(keys, count);
+
+            while ((he = hv_iternext(hval))) {
+                av_push(keys, SvREFCNT_inc(hv_iterkeysv(he)));
+            }
+
+            int len = av_len(keys) + 1;
+            sortsv(AvARRAY(keys), len, Perl_sv_cmp);
+
+            int i;
+            for (i=0; i<len; i++) {
+                SV** svp = av_fetch(keys, i, FALSE);
+                he = hv_fetch_ent(hval, *svp, 0, 0);
+
+                _msgpack_pack_sv(enc, hv_iterkeysv(he), depth);
+                _msgpack_pack_sv(enc, HeVAL(he), depth);
+            }
+
+            av_undef(keys);
+        } else {
+            while ((he = hv_iternext(hval))) {
+                _msgpack_pack_sv(enc, hv_iterkeysv(he), depth);
+                _msgpack_pack_sv(enc, HeVAL(he), depth);
+            }
         }
     } else if (svt == SVt_PVAV) {
         AV* ary = (AV*)sv;