diff --git a/phpBB/docs/CHANGELOG.html b/phpBB/docs/CHANGELOG.html
index 0d45c5f5ca..a2eae1961f 100644
--- a/phpBB/docs/CHANGELOG.html
+++ b/phpBB/docs/CHANGELOG.html
@@ -113,6 +113,7 @@
 		<li>[Fix] Expand shown ban reason in unban screen to fully show long entries. (Bug #16234)</li>
 		<li>[Fix] Preserve alpha transparency for created thumbnails. (Bug #16575)</li>
 		<li>[Fix] Use correct port delimiter for MSSQL connections in windows. (Bug #16615)</li>
+		<li>[Fix] Do not allow setting forums parent to the forum itself. (Bug #18855)</li>
 
 		<li>[Change] No longer allow the direct use of MULTI_INSERT in sql_build_array. sql_multi_insert() must be used.</li>
 		<li>[Change] Display warning in ACP if config.php file is left writable.</li>
diff --git a/phpBB/includes/acp/acp_forums.php b/phpBB/includes/acp/acp_forums.php
index fa07c00dee..5b4d0939d4 100644
--- a/phpBB/includes/acp/acp_forums.php
+++ b/phpBB/includes/acp/acp_forums.php
@@ -922,10 +922,9 @@ class acp_forums
 		$range_test_ary = array(
 			array('lang' => 'FORUM_TOPICS_PAGE', 'value' => $forum_data['forum_topics_per_page'], 'column_type' => 'TINT:0'),
 		);
+
 		validate_range($range_test_ary, $errors);
 
-
-
 		// Set forum flags
 		// 1 = link tracking
 		// 2 = prune old polls
@@ -1206,7 +1205,14 @@ class acp_forums
 
 			if ($row['parent_id'] != $forum_data_sql['parent_id'])
 			{
-				$errors = $this->move_forum($forum_data_sql['forum_id'], $forum_data_sql['parent_id']);
+				if ($row['forum_id'] != $forum_data_sql['parent_id'])
+				{
+					$errors = $this->move_forum($forum_data_sql['forum_id'], $forum_data_sql['parent_id']);
+				}
+				else
+				{
+					$forum_data_sql['parent_id'] = $row['parent_id'];
+				}
 			}
 
 			if (sizeof($errors))