diff --git a/phpBB/includes/functions.php b/phpBB/includes/functions.php
index c2b099d48a..e477b0454e 100644
--- a/phpBB/includes/functions.php
+++ b/phpBB/includes/functions.php
@@ -3486,6 +3486,10 @@ function get_preg_expression($mode)
 			$inline = ($mode == 'relative_url') ? ')' : '';
 			return "(?:[a-z0-9\-._~!$&'($inline*+,;=:@|]+|%[\dA-F]{2})*(?:/(?:[a-z0-9\-._~!$&'($inline*+,;=:@|]+|%[\dA-F]{2})*)*(?:\?(?:[a-z0-9\-._~!$&'($inline*+,;=:@/?|]+|%[\dA-F]{2})*)?(?:\#(?:[a-z0-9\-._~!$&'($inline*+,;=:@/?|]+|%[\dA-F]{2})*)?";
 		break;
+
+		case 'table_prefix':
+			return '#^[a-zA-Z][a-zA-Z0-9_]*$#';
+		break;
 	}
 
 	return '';
diff --git a/phpBB/install/install_install.php b/phpBB/install/install_install.php
index bb1d858cfc..ccdcf211f1 100644
--- a/phpBB/install/install_install.php
+++ b/phpBB/install/install_install.php
@@ -546,7 +546,7 @@ class install_install extends module
 				$error[] = $lang['INST_ERR_NO_DB'];
 				$connect_test = false;
 			}
-			else if (!preg_match('#^[a-zA-Z][a-zA-Z0-9_]*$#', $data['table_prefix'], $result))
+			else if (!preg_match(get_preg_expression('table_prefix'), $data['table_prefix']))
 			{
 				$error[] = $lang['INST_ERR_DB_INVALID_PREFIX'];
 				$connect_test = false;
diff --git a/tests/regex/table_prefix_test.php b/tests/regex/table_prefix_test.php
new file mode 100644
index 0000000000..67a18b4fbc
--- /dev/null
+++ b/tests/regex/table_prefix_test.php
@@ -0,0 +1,35 @@
+<?php
+/**
+*
+* @package testing
+* @copyright (c) 2011 phpBB Group
+* @license http://opensource.org/licenses/gpl-license.php GNU Public License
+*
+*/
+
+require_once dirname(__FILE__) . '/../../phpBB/includes/functions.php';
+
+class phpbb_regex_table_prefix_test extends phpbb_test_case
+{
+	public function table_prefix_test_data()
+	{
+		return array(
+			array('phpbb_', 1),
+			array('phpBB3', 1),
+			array('a', 1),
+
+			array('', 0),
+			array('_', 0),
+			array('a-', 0),
+			array("'", 0),
+		);
+	}
+
+	/**
+	* @dataProvider table_prefix_test_data
+	*/
+	public function test_table_prefix($prefix, $expected)
+	{
+		$this->assertEquals($expected, preg_match(get_preg_expression('table_prefix'), $prefix));
+	}
+}