diff --git a/phpBB/phpbb/db/migration/data/v31x/profilefield_remove_underscore_from_alpha.php b/phpBB/phpbb/db/migration/data/v31x/profilefield_remove_underscore_from_alpha.php
new file mode 100644
index 0000000000..1f25d239a6
--- /dev/null
+++ b/phpBB/phpbb/db/migration/data/v31x/profilefield_remove_underscore_from_alpha.php
@@ -0,0 +1,47 @@
+<?php
+
+/**
+ *
+ * This file is part of the phpBB Forum Software package.
+ *
+ * @copyright (c) phpBB Limited <https://www.phpbb.com>
+ * @license GNU General Public License, version 2 (GPL-2.0)
+ *
+ * For full copyright and license information, please see
+ * the docs/CREDITS.txt file.
+ *
+ */
+
+namespace phpbb\db\migration\data\v31x;
+
+class profilefield_remove_underscore_from_alpha extends \phpbb\db\migration\migration
+{
+	static public function depends_on()
+	{
+		return array('\phpbb\db\migration\data\v31x\v311');
+	}
+
+	public function update_data()
+	{
+		return array(
+			array('custom', array(array($this, 'remove_underscore_from_alpha_validations'))),
+		);
+	}
+
+	public function remove_underscore_from_alpha_validations()
+	{
+		$this->update_validation_rule('[\w]+', '[a-zA-Z0-9]+');
+		$this->update_validation_rule('[\w_]+', '[\w]+');
+		$this->update_validation_rule('[\w.]+', '[a-zA-Z0-9.]+');
+		$this->update_validation_rule('[\w\x20_+\-\[\]]+', '[\w\x20+\-\[\]]+');
+		$this->update_validation_rule('[a-zA-Z][\w\.,\-_]+', '[a-zA-Z][\w\.,\-]+');
+	}
+
+	public function update_validation_rule($old_validation, $new_validation)
+	{
+		$sql = 'UPDATE ' . PROFILE_FIELDS_TABLE . "
+			SET field_validation = '" . $this->db->sql_escpape($new_validation) . "'
+			WHERE field_validation = '" . $this->db->sql_escpape($old_validation) . "'";
+		$this->db->sql_query($sql);
+	}
+}