diff --git a/lib/mysql.js b/lib/mysql.js
index 1015465..3390a56 100644
--- a/lib/mysql.js
+++ b/lib/mysql.js
@@ -716,6 +716,20 @@ MySQL.prototype.isActual = function(cb) {
   });
 };
 
+// Check if a property is nullable
+function isNullable(p) {
+  if (p.required || p.id) {
+    return false;
+  }
+  if (p.nullable || p['null'] || p.allowNull) {
+    return true;
+  }
+  if (p.nullable === false || p['null'] === false || p.allowNull === false) {
+    return false;
+  }
+  return true;
+}
+
 MySQL.prototype.alterTable = function (model, actualFields, actualIndexes, done, checkOnly) {
   var self = this;
   var m = this._models[model];
@@ -856,7 +870,8 @@ MySQL.prototype.alterTable = function (model, actualFields, actualIndexes, done,
   function actualize(propName, oldSettings) {
     var newSettings = m.properties[propName];
     if (newSettings && changed(newSettings, oldSettings)) {
-      sql.push('CHANGE COLUMN `' + propName + '` `' + propName + '` ' + self.propertySettingsSQL(model, propName));
+      sql.push('CHANGE COLUMN `' + propName + '` `' + propName + '` ' +
+        self.propertySettingsSQL(model, propName));
     }
   }
 
@@ -864,14 +879,21 @@ MySQL.prototype.alterTable = function (model, actualFields, actualIndexes, done,
     if (oldSettings.Null === 'YES') { // Used to allow null and does not now.
       if (newSettings.allowNull === false) return true;
       if (newSettings.null === false) return true;
+      if (newSettings.nullable === false) return true;
+      if (newSettings.required || newSettings.id) return true;
     }
     if (oldSettings.Null === 'NO') { // Did not allow null and now does.
       if (newSettings.allowNull === true) return true;
       if (newSettings.null === true) return true;
-      if (newSettings.null === undefined && newSettings.allowNull === undefined) return true;
+      if (newSettings.nullable === true) return true;
+      if (newSettings.null === undefined &&
+        newSettings.allowNull === undefined &&
+        !newSettings.required &&
+        !newSettings.id) return true;
     }
 
-    if (oldSettings.Type.toUpperCase() !== datatype(newSettings).toUpperCase()) return true;
+    if (oldSettings.Type.toUpperCase() !== datatype(newSettings).toUpperCase())
+      return true;
     return false;
   }
 };
@@ -971,7 +993,9 @@ MySQL.prototype.indexSettingsSQL = function (model, prop) {
 MySQL.prototype.propertySettingsSQL = function (model, prop) {
   var p = this._models[model].properties[prop];
   var line = this.columnDataType(model, prop) + ' ' +
-    (p.nullable === false || p.allowNull === false || p['null'] === false ? 'NOT NULL' : 'NULL');
+    (p.required || p.id || p.nullable === false ||
+      p.allowNull === false || p['null'] === false ?
+      'NOT NULL' : 'NULL');
   return line;
 };
 
diff --git a/test/migration.test.js b/test/migration.test.js
index ce35c69..5b23430 100644
--- a/test/migration.test.js
+++ b/test/migration.test.js
@@ -72,7 +72,8 @@ describe('migrations', function () {
   });
 
   it('UserData should have correct indexes', function (done) {
-    // Note: getIndexes truncates multi-key indexes to the first member. Hence index1 is correct.
+    // Note: getIndexes truncates multi-key indexes to the first member.
+    // Hence index1 is correct.
     getIndexes('UserData', function (err, fields) {
       assert.deepEqual(fields, { PRIMARY: { Table: 'UserData',
         Non_unique: 0,
@@ -182,7 +183,7 @@ describe('migrations', function () {
           Extra: '' },
         mediumInt: { Field: 'mediumInt',
           Type: 'mediumint(8) unsigned',
-          Null: 'YES',
+          Null: 'NO',
           Key: '',
           Default: null,
           Extra: '' },
@@ -236,9 +237,12 @@ describe('migrations', function () {
         assert.ok(yep, 'User does not exist');
       });
       UserData.defineProperty('email', { type: String });
-      UserData.defineProperty('name', {type: String, dataType: 'char', limit: 50});
-      UserData.defineProperty('newProperty', {type: Number, unsigned: true, dataType: 'bigInt'});
-      // UserData.defineProperty('pendingPeriod', false); This will not work as expected.
+      UserData.defineProperty('name', {type: String,
+        dataType: 'char', limit: 50});
+      UserData.defineProperty('newProperty', {type: Number, unsigned: true,
+        dataType: 'bigInt'});
+      // UserData.defineProperty('pendingPeriod', false);
+      // This will not work as expected.
       db.autoupdate(function (err) {
         getFields('UserData', function (err, fields) {
           // change nullable for email
@@ -248,10 +252,12 @@ describe('migrations', function () {
           // add new column
           assert.ok(fields.newProperty, 'New column was not added');
           if (fields.newProperty) {
-            assert.equal(fields.newProperty.Type, 'bigint(20) unsigned', 'New column type is not bigint(20) unsigned');
+            assert.equal(fields.newProperty.Type, 'bigint(20) unsigned',
+              'New column type is not bigint(20) unsigned');
           }
           // drop column - will not happen.
-          // assert.ok(!fields.pendingPeriod, 'Did not drop column pendingPeriod');
+          // assert.ok(!fields.pendingPeriod,
+          // 'Did not drop column pendingPeriod');
           // user still exists
           userExists(function (yep) {
             assert.ok(yep, 'User does not exist');
@@ -276,7 +282,8 @@ describe('migrations', function () {
   });
 
   it('should allow numbers with decimals', function (done) {
-    NumberData.create({number: 1.1234567, tinyInt: 123456, mediumInt: -1234567, floater: 123456789.1234567 }, function (err, obj) {
+    NumberData.create({number: 1.1234567, tinyInt: 123456, mediumInt: -1234567,
+      floater: 123456789.1234567 }, function (err, obj) {
       assert.ok(!err);
       assert.ok(obj);
       NumberData.findById(obj.id, function (err, found) {
@@ -297,8 +304,10 @@ describe('migrations', function () {
       assert.ok(!err);
       assert.ok(obj);
       DateData.findById(obj.id, function (err, found) {
-        assert.equal(found.dateTime.toGMTString(), 'Fri, 09 Aug 1996 07:47:33 GMT');
-        assert.equal(found.timestamp.toGMTString(), 'Sat, 22 Sep 2007 17:12:22 GMT');
+        assert.equal(found.dateTime.toGMTString(),
+          'Fri, 09 Aug 1996 07:47:33 GMT');
+        assert.equal(found.timestamp.toGMTString(),
+          'Sat, 22 Sep 2007 17:12:22 GMT');
         done();
       });
     });
@@ -345,7 +354,8 @@ function setup(done) {
 
   StringData = db.define('StringData', {
     idString: {type: String, id: true},
-    smallString: {type: String, null: false, index: true, dataType: 'char', limit: 127},
+    smallString: {type: String, null: false, index: true,
+      dataType: 'char', limit: 127},
     mediumString: {type: String, null: false, dataType: 'varchar', limit: 255},
     tinyText: {type: String, dataType: 'tinyText'},
     giantJSON: {type: Schema.JSON, dataType: 'longText'},
@@ -353,9 +363,11 @@ function setup(done) {
   });
 
   NumberData = db.define('NumberData', {
-    number: {type: Number, null: false, index: true, unsigned: true, dataType: 'decimal', precision: 10, scale: 3},
+    number: {type: Number, null: false, index: true, unsigned: true,
+      dataType: 'decimal', precision: 10, scale: 3},
     tinyInt: {type: Number, dataType: 'tinyInt', display: 2},
-    mediumInt: {type: Number, dataType: 'mediumInt', unsigned: true},
+    mediumInt: {type: Number, dataType: 'mediumInt', unsigned: true,
+      required: true},
     floater: {type: Number, dataType: 'double', precision: 14, scale: 6}
   });