diff --git a/src/binformat.js b/src/binformat.js
index d1897b15..c93ad184 100644
--- a/src/binformat.js
+++ b/src/binformat.js
@@ -224,7 +224,9 @@ var base = [
   [ 'Fee'                , REQUIRED ],
   [ 'OperationLimit'     , OPTIONAL ],
   [ 'SigningPubKey'      , REQUIRED ],
-  [ 'TxnSignature'       , OPTIONAL ]
+  [ 'TxnSignature'       , OPTIONAL ],
+  [ 'AccountTxnID'       , OPTIONAL ],
+  [ 'Memos'              , OPTIONAL ]
 ];
 
 exports.tx = {
diff --git a/src/serializedobject.js b/src/serializedobject.js
index 8766f27f..e97248c6 100644
--- a/src/serializedobject.js
+++ b/src/serializedobject.js
@@ -97,39 +97,60 @@ SerializedObject.from_json = function(obj) {
   }
 
   // ND: This from_*json* seems a reasonable place to put validation of `json`
-  SerializedObject.check_no_missing_fields(typedef, obj);
+  SerializedObject.check_fields(typedef, obj);
   so.serialize(typedef, obj);
 
   return so;
 };
 
-SerializedObject.check_no_missing_fields = function(typedef, obj) {
-  var missing_fields = [];
+SerializedObject.check_fields = function(typedef, obj) {
+  let missingFields = [];
+  let unknownFields = [];
+  let fieldsMap = {};
 
-  for (var i = typedef.length - 1; i >= 0; i--) {
-    var spec = typedef[i];
-    var field = spec[0];
-    var requirement = spec[1];
+  // Get missing required fields
+  typedef.forEach(function(field) {
+    var fieldName = field[0];
+    var isRequired = field[1] === binformat.REQUIRED;
 
-    if (binformat.REQUIRED === requirement && obj[field] === undefined) {
-      missing_fields.push(field);
-    }
-  }
-
-  if (missing_fields.length > 0) {
-    var object_name;
-
-    if (obj.TransactionType !== undefined) {
-      object_name = SerializedObject.lookup_type_tx(obj.TransactionType);
-    } else if (obj.LedgerEntryType !== undefined) {
-      object_name = SerializedObject.lookup_type_le(obj.LedgerEntryType);
+    if (isRequired && obj[fieldName] === undefined) {
+      missingFields.push(fieldName);
     } else {
-      object_name = 'TransactionMetaData';
+      fieldsMap[fieldName] = true;
     }
+  });
 
-    throw new Error(object_name + ' is missing fields: ' +
-                    JSON.stringify(missing_fields));
+  // Get fields that are not specified in format
+  Object.keys(obj).forEach(function(key) {
+    if (!fieldsMap[key] && /^[A-Z]/.test(key)) {
+      unknownFields.push(key);
+    }
+  });
+
+  if (!(missingFields.length || unknownFields.length)) {
+    // No missing or unknown fields
+    return;
   }
+
+  var errorMessage;
+
+  if (obj.TransactionType !== undefined) {
+    errorMessage = SerializedObject.lookup_type_tx(obj.TransactionType);
+  } else if (obj.LedgerEntryType !== undefined) {
+    errorMessage = SerializedObject.lookup_type_le(obj.LedgerEntryType);
+  } else {
+    errorMessage = 'TransactionMetaData';
+  }
+
+  if (missingFields.length > 0) {
+    errorMessage += ' is missing fields: ' + JSON.stringify(missingFields);
+  }
+  if (unknownFields.length > 0) {
+     errorMessage += (missingFields.length ? ' and' : '')
+     + ' has unknown fields: ' + JSON.stringify(unknownFields);
+  }
+
+  throw new Error(errorMessage);
 };
 
 SerializedObject.prototype.append = function(bytes) {
diff --git a/test/serializedobject-test.js b/test/serializedobject-test.js
index 13e8a150..b5bd84dd 100644
--- a/test/serializedobject-test.js
+++ b/test/serializedobject-test.js
@@ -12,6 +12,7 @@
 /* eslint-disable quotes*/
 
 var assert = require('assert');
+var lodash = require('lodash');
 var SerializedObject = require('ripple-lib').SerializedObject;
 var Amount = require('ripple-lib').Amount;
 var sjcl = require('ripple-lib').sjcl;
@@ -150,6 +151,52 @@ describe('Serialized object', function() {
       assert.equal("DirectoryNode", output_json.LedgerEntryType);
     });
 
+    it('checks for missing required fields', function() {
+      var input_json = {
+        TransactionType: 'Payment',
+        // no non required fields
+        Account: 'r4qLSAzv4LZ9TLsR7diphGwKnSEAMQTSjS',
+        Amount: '274579388',
+        Destination: 'r4qLSAzv4LZ9TLsR7diphGwKnSEAMQTSjS',
+        Fee: '15',
+        Sequence: 351,
+        SigningPubKey: '02'
+      };
+
+      Object.keys(input_json).slice(1).forEach(function(k) {
+        var bad_json = lodash.merge({}, input_json);
+        delete bad_json[k];
+
+        assert.strictEqual(bad_json[k], undefined);
+        assert.throws(function() {
+          SerializedObject.from_json(bad_json);
+        }, new RegExp('Payment is missing fields: \\["' + k + '"\\]'));
+
+      });
+    });
+    it('checks for unknown fields', function() {
+      var input_json = {
+        TransactionType: 'Payment',
+        // no non required fields
+        Account: 'r4qLSAzv4LZ9TLsR7diphGwKnSEAMQTSjS',
+        Amount: '274579388',
+        Destination: 'r4qLSAzv4LZ9TLsR7diphGwKnSEAMQTSjS',
+        Fee: '15',
+        Sequence: 351,
+        SigningPubKey: '02'
+      };
+
+      Object.keys(input_json).slice(1).forEach(function(k) {
+        var bad_json = lodash.merge({}, input_json);
+        bad_json[k + 'z'] = bad_json[k];
+
+        assert.throws(function() {
+          SerializedObject.from_json(bad_json);
+        }, new RegExp('Payment has unknown fields: \\["' + k + 'z"\\]'));
+
+      });
+    });
+
     describe('Format validation', function() {
       // Peercover actually had a problem submitting transactions without a `Fee`
       // and rippled was only informing of "transaction is invalid"