diff --git a/phpBB/includes/functions.php b/phpBB/includes/functions.php
index e3feb59d41..65d8be32ad 100644
--- a/phpBB/includes/functions.php
+++ b/phpBB/includes/functions.php
@@ -1297,93 +1297,6 @@ function tz_select($default = '', $truncate = false)
 	return $tz_select;
 }
 
-/**
-* Updates rows in given table from a set of values to a new value.
-* If this results in rows violating uniqueness constraints, the duplicate
-* rows are eliminated.
-*
-* The only supported tables are bookmarks and topics_watch.
-*
-* @param dbal $db Database object
-* @param string $table Table on which to perform the update
-* @param string $column Column whose values to change
-* @param array $from_values An array of values that should be changed
-* @param int $to_value The new value
-* @return null
-*/
-function phpbb_update_rows_avoiding_duplicates($db, $table, $column, $from_values, $to_value)
-{
-	$sql = "SELECT $column, user_id
-		FROM $table
-		WHERE " . $db->sql_in_set($column, $from_values);
-	$result = $db->sql_query($sql);
-
-	$old_user_ids = array();
-	while ($row = $db->sql_fetchrow($result))
-	{
-		$old_user_ids[$row[$column]][] = $row['user_id'];
-	}
-	$db->sql_freeresult($result);
-
-	$sql = "SELECT $column, user_id
-		FROM $table
-		WHERE $column = '" . (int) $to_value . "'";
-	$result = $db->sql_query($sql);
-
-	$new_user_ids = array();
-	while ($row = $db->sql_fetchrow($result))
-	{
-		$new_user_ids[$row[$column]][] = $row['user_id'];
-	}
-	$db->sql_freeresult($result);
-
-	$queries = array();
-	$any_found = false;
-	foreach ($from_values as $from_value)
-	{
-		if (!isset($old_user_ids[$from_value]))
-		{
-			continue;
-		}
-		$any_found = true;
-		if (empty($new_user_ids))
-		{
-			$sql = "UPDATE $table
-				SET $column = " . (int) $to_value. "
-				WHERE $column = '" . $db->sql_escape($from_value) . "'";
-			$queries[] = $sql;
-		}
-		else
-		{
-			$different_user_ids = array_diff($old_user_ids[$from_value], $new_user_ids[$to_value]);
-			if (!empty($different_user_ids))
-			{
-				$sql = "UPDATE $table
-					SET $column = " . (int) $to_value. "
-					WHERE $column = '" . $db->sql_escape($from_value) . "'
-					AND " . $db->sql_in_set('user_id', $different_user_ids);
-				$queries[] = $sql;
-			}
-		}
-	}
-
-	if ($any_found)
-	{
-		$db->sql_transaction('begin');
-
-		foreach ($queries as $sql)
-		{
-			$db->sql_query($sql);
-		}
-
-		$sql = "DELETE FROM $table
-			WHERE " . $db->sql_in_set($column, $from_values);
-		$db->sql_query($sql);
-
-		$db->sql_transaction('commit');
-	}
-}
-
 // Functions handling topic/post tracking/marking
 
 /**
diff --git a/phpBB/includes/functions_tricky_update.php b/phpBB/includes/functions_tricky_update.php
new file mode 100644
index 0000000000..a5b9fdacd0
--- /dev/null
+++ b/phpBB/includes/functions_tricky_update.php
@@ -0,0 +1,103 @@
+<?php
+/**
+*
+* @package phpBB3
+* @copyright (c) 2012 phpBB Group
+* @license http://opensource.org/licenses/gpl-2.0.php GNU General Public License v2
+*
+*/
+
+/**
+* @ignore
+*/
+if (!defined('IN_PHPBB'))
+{
+	exit;
+}
+
+/**
+* Updates rows in given table from a set of values to a new value.
+* If this results in rows violating uniqueness constraints, the duplicate
+* rows are eliminated.
+*
+* The only supported tables are bookmarks and topics_watch.
+*
+* @param dbal $db Database object
+* @param string $table Table on which to perform the update
+* @param string $column Column whose values to change
+* @param array $from_values An array of values that should be changed
+* @param int $to_value The new value
+* @return null
+*/
+function phpbb_update_rows_avoiding_duplicates($db, $table, $column, $from_values, $to_value)
+{
+	$sql = "SELECT $column, user_id
+		FROM $table
+		WHERE " . $db->sql_in_set($column, $from_values);
+	$result = $db->sql_query($sql);
+
+	$old_user_ids = array();
+	while ($row = $db->sql_fetchrow($result))
+	{
+		$old_user_ids[$row[$column]][] = $row['user_id'];
+	}
+	$db->sql_freeresult($result);
+
+	$sql = "SELECT $column, user_id
+		FROM $table
+		WHERE $column = '" . (int) $to_value . "'";
+	$result = $db->sql_query($sql);
+
+	$new_user_ids = array();
+	while ($row = $db->sql_fetchrow($result))
+	{
+		$new_user_ids[$row[$column]][] = $row['user_id'];
+	}
+	$db->sql_freeresult($result);
+
+	$queries = array();
+	$any_found = false;
+	foreach ($from_values as $from_value)
+	{
+		if (!isset($old_user_ids[$from_value]))
+		{
+			continue;
+		}
+		$any_found = true;
+		if (empty($new_user_ids))
+		{
+			$sql = "UPDATE $table
+				SET $column = " . (int) $to_value. "
+				WHERE $column = '" . $db->sql_escape($from_value) . "'";
+			$queries[] = $sql;
+		}
+		else
+		{
+			$different_user_ids = array_diff($old_user_ids[$from_value], $new_user_ids[$to_value]);
+			if (!empty($different_user_ids))
+			{
+				$sql = "UPDATE $table
+					SET $column = " . (int) $to_value. "
+					WHERE $column = '" . $db->sql_escape($from_value) . "'
+					AND " . $db->sql_in_set('user_id', $different_user_ids);
+				$queries[] = $sql;
+			}
+		}
+	}
+
+	if ($any_found)
+	{
+		$db->sql_transaction('begin');
+
+		foreach ($queries as $sql)
+		{
+			$db->sql_query($sql);
+		}
+
+		$sql = "DELETE FROM $table
+			WHERE " . $db->sql_in_set($column, $from_values);
+		$db->sql_query($sql);
+
+		$db->sql_transaction('commit');
+	}
+}
diff --git a/tests/functions/fixtures/duplicates.xml b/tests/functions_tricky_update/fixtures/duplicates.xml
similarity index 100%
rename from tests/functions/fixtures/duplicates.xml
rename to tests/functions_tricky_update/fixtures/duplicates.xml
diff --git a/tests/functions/update_rows_avoiding_duplicates_test.php b/tests/functions_tricky_update/update_rows_avoiding_duplicates_test.php
similarity index 98%
rename from tests/functions/update_rows_avoiding_duplicates_test.php
rename to tests/functions_tricky_update/update_rows_avoiding_duplicates_test.php
index 0d68e22d4a..6940122393 100644
--- a/tests/functions/update_rows_avoiding_duplicates_test.php
+++ b/tests/functions_tricky_update/update_rows_avoiding_duplicates_test.php
@@ -7,7 +7,7 @@
 *
 */
 
-require_once dirname(__FILE__) . '/../../phpBB/includes/functions.php';
+require_once dirname(__FILE__) . '/../../phpBB/includes/functions_tricky_update.php';
 
 class phpbb_update_rows_avoiding_duplicates_test extends phpbb_database_test_case
 {