diff --git a/system/database/drivers/mssql/mssql_driver.php b/system/database/drivers/mssql/mssql_driver.php
index 4d29920..611a4af 100644
--- a/system/database/drivers/mssql/mssql_driver.php
+++ b/system/database/drivers/mssql/mssql_driver.php
@@ -300,7 +300,7 @@
 	* @param	string	$version
 	* @return	int	major version number
 	*/
-	private function _parse_major_version($version)
+	protected function _parse_major_version($version)
 	{
 		preg_match('/([0-9]+)\.([0-9]+)\.([0-9]+)/', $version, $ver_info);
 		return $ver_info[1]; // return the major version b/c that's all we're interested in.
diff --git a/system/database/drivers/mssql/mssql_forge.php b/system/database/drivers/mssql/mssql_forge.php
index 231284c..59b930c 100644
--- a/system/database/drivers/mssql/mssql_forge.php
+++ b/system/database/drivers/mssql/mssql_forge.php
@@ -80,7 +80,7 @@
 	 * @param	array	the fields
 	 * @param	mixed	primary key(s)
 	 * @param	mixed	key(s)
-	 * @param	boolean	should 'IF NOT EXISTS' be added to the SQL
+	 * @param	bool	should 'IF NOT EXISTS' be added to the SQL
 	 * @return	string
 	 */
 	public function _create_table($table, $fields, $primary_keys, $keys, $if_not_exists)
@@ -110,11 +110,11 @@
 
 				$sql .= "\n\t".$this->db->protect_identifiers($field)
 					.' '.$attributes['TYPE']
-					.(isset($attributes['CONSTRAINT']) ? '('.$attributes['CONSTRAINT'].')' : '')
-					.((isset($attributes['UNSIGNED']) && $attributes['UNSIGNED'] === TRUE) ? ' UNSIGNED' : '')
+					.( ! empty($attributes['CONSTRAINT']) ? '('.$attributes['CONSTRAINT'].')' : '')
+					.(( ! empty($attributes['UNSIGNED']) && $attributes['UNSIGNED'] === TRUE) ? ' UNSIGNED' : '')
 					.(isset($attributes['DEFAULT']) ? ' DEFAULT \''.$attributes['DEFAULT'].'\'' : '')
-					.((isset($attributes['NULL']) && $attributes['NULL'] === TRUE) ? ' NULL' : ' NOT NULL')
-					.((isset($attributes['AUTO_INCREMENT']) && $attributes['AUTO_INCREMENT'] === TRUE) ? ' AUTO_INCREMENT' : '');
+					.(( ! empty($attributes['NULL']) && $attributes['NULL'] === TRUE) ? ' NULL' : ' NOT NULL')
+					.(( ! empty($attributes['AUTO_INCREMENT']) && $attributes['AUTO_INCREMENT'] === TRUE) ? ' AUTO_INCREMENT' : '');
 			}
 
 			// don't add a comma on the end of the last field
@@ -163,9 +163,9 @@
 	 * @param	string	the table name
 	 * @param	string	the column definition
 	 * @param	string	the default value
-	 * @param	boolean	should 'NOT NULL' be added
+	 * @param	bool	should 'NOT NULL' be added
 	 * @param	string	the field after which we should add the new field
-	 * @return	object
+	 * @return	string
 	 */
 	public function _alter_table($alter_type, $table, $column_name, $column_definition = '', $default_value = '', $null = '', $after_field = '')
 	{