diff --git a/scripts/app/FixParser.js b/scripts/app/FixParser.js
index a517bdf..4f95df4 100644
--- a/scripts/app/FixParser.js
+++ b/scripts/app/FixParser.js
@@ -160,6 +160,47 @@ define(
                 }
             );
 
+            // Checksum(10) verification
+            _.each(
+                messages,
+                function(message)
+                {
+                    var field_checksum = undefined;
+                    sum = 0;
+
+                    _.each(
+                        message.fields,
+                        function(field)
+                        {
+                            if ( field.fieldId == FIELD_CHECKSUM ) {
+                                field_checksum = field;
+                                return;
+                            }
+
+                            for ( var i = 0 ; i < field.raw.length ; i++ ) {
+                                sum += field.raw.charCodeAt(i);
+                            }
+                        }
+                    );
+
+                    // Modulo 256 + pad up to 3 characters with zero
+                    sum = ("00" + (sum % 256)).slice(-3);
+
+                    if ( ! field_checksum ) {
+                        return;
+                    }
+
+                    if ( field_checksum.value == sum ) {
+                        field_checksum.classes += ' valid';
+                        field_checksum.decodedValue = 'Valid';
+                    }
+                    else {
+                        field_checksum.classes += ' invalid';
+                        field_checksum.decodedValue = '/!\\ Invalid (expected ' + sum + ')';
+                    }
+                }
+            );
+
             return messages;
         };
 
diff --git a/scripts/app/main.js b/scripts/app/main.js
index 82aa667..e9fea6b 100644
--- a/scripts/app/main.js
+++ b/scripts/app/main.js
@@ -137,12 +137,12 @@ define(
         $('#clear').click(function() { input.val(''); return false; });
 
         var sampleMessages = [
-            'outgoing: 8=FIX.4.2|9=178|35=AE|56=LSEHub|49=BROKERX|128=LSETR|34=2175|52=20120126-15:15:54|918=GBP|31=89.0000000|64=20120126|828=1|60=20120126-13:32:49|32=6|22=4|571=124|43=N|570=N|150=0|48=GB0007188757|10=017|\n' +
-            'incoming: 8=FIX.4.2|9=112|35=AR|49=LSEHub|56=BROKERX|115=LSETR|34=2006|52=20120126-15:15:54|370=20120126-15:15:54.822|571=124|150=0|939=0|10=126|',
-            'outgoing: 8=FIX.4.2|9=130|35=AE|49=LSEHub|56=LSETR|115=BROKERX|34=2287|43=N|52=20120330-12:14:09|370=20120330-12:14:09.816|571=00008661533TRLO1-1-1-0|150=H|10=113|\n' +
-            'incoming: 8=FIX.4.2|9=109|35=AR|34=2486|49=LSETR|52=20120330-12:14:10.379|56=LSEHub|128=BROKERX|150=H|571=00008661533TRLO1-1-1-0|939=0|10=103|',
-            'outgoing: 8=FIX.4.2|9=175|35=AE|49=BROKERX|56=LSEHub|34=17|52=20120202-16:04:44|128=LSETR|918=EUR|31=89.0000000|64=20120202|828=1007|60=20120202-16:04:44|32=6|22=4|571=1698|570=N|150=0|48=AT0000785555|10=087|\n' +
-            'incoming: 8=FIX.4.2|9=111|35=AR|49=LSEHub|56=BROKERX|115=LSETR|34=16|52=20120202-16:04:44|370=20120202-16:04:45.257|571=1698|150=0|939=0|10=026|'
+            'outgoing: 8=FIX.4.2|9=178|35=AE|56=LSEHub|49=BROKERX|128=LSETR|34=2175|52=20120126-15:15:54|918=GBP|31=89.0000000|64=20120126|828=1|60=20120126-13:32:49|32=6|22=4|571=124|43=N|570=N|150=0|48=GB0007188757|10=206|\n' +
+            'incoming: 8=FIX.4.2|9=112|35=AR|49=LSEHub|56=BROKERX|115=LSETR|34=2006|52=20120126-15:15:54|370=20120126-15:15:54.822|571=124|150=0|939=0|10=059|',
+            'outgoing: 8=FIX.4.2|9=130|35=AE|49=LSEHub|56=LSETR|115=BROKERX|34=2287|43=N|52=20120330-12:14:09|370=20120330-12:14:09.816|571=00008661533TRLO1-1-1-0|150=H|10=074|\n' +
+            'incoming: 8=FIX.4.2|9=109|35=AR|34=2486|49=LSETR|52=20120330-12:14:10.379|56=LSEHub|128=BROKERX|150=H|571=00008661533TRLO1-1-1-0|939=0|10=073|',
+            'outgoing: 8=FIX.4.2|9=175|35=AE|49=BROKERX|56=LSEHub|34=17|52=20120202-16:04:44|128=LSETR|918=EUR|31=89.0000000|64=20120202|828=1007|60=20120202-16:04:44|32=6|22=4|571=1698|570=N|150=0|48=AT0000785555|10=076|\n' +
+            'incoming: 8=FIX.4.2|9=111|35=AR|49=LSEHub|56=BROKERX|115=LSETR|34=16|52=20120202-16:04:44|370=20120202-16:04:45.257|571=1698|150=0|939=0|10=015|'
         ];
 
         $('a.sample-message-link').click(function()
diff --git a/styles/styles.css b/styles/styles.css
index e1ba22a..761732e 100644
--- a/styles/styles.css
+++ b/styles/styles.css
@@ -120,11 +120,13 @@ tr.system-field
     color: #aaa;
 }
 
+tr.system-field.valid .field-value,
 tr.header-field.valid .field-value
 {
     color: #0c0;
 }
 
+tr.system-field.invalid .field-value,
 tr.header-field.invalid .field-value
 {
     color: #f00;