diff --git a/phpBB/docs/CHANGELOG.html b/phpBB/docs/CHANGELOG.html
index f43d08c8e1..ab3f01af71 100644
--- a/phpBB/docs/CHANGELOG.html
+++ b/phpBB/docs/CHANGELOG.html
@@ -120,6 +120,7 @@
 		<li>[Fix] Fix wrong bot ip check if bot ip was wrongly entered by admin. (Bug #42485)</li>
 		<li>[Fix] Fix javascript errors in simple header (prosilver) by adding forum_fn.js and the corresponding variables. (Bug #42135)</li>
 		<li>[Fix] Set connection encoding for MySQL versions 4.1.0 to 4.1.2. This may fix some conversion issues with special characters. (Bug #41805)</li>
+		<li>[Fix] Deleting private message attachments could delete post attachments. (Bug #42815)</li>
 		<li>[Change] Allow download of conflicting file for later reference in automatic updater</li>
 		<li>[Change] Default difference view is now 'inline' instead of 'side by side'</li>
 		<li>[Change] Added new option for merging differences to conflicting files in automatic updater</li>
@@ -861,4 +862,4 @@
 </div>
 
 </body>
-</html>
\ No newline at end of file
+</html>
diff --git a/phpBB/includes/functions_admin.php b/phpBB/includes/functions_admin.php
index 5ec51e44cf..5da18d250c 100644
--- a/phpBB/includes/functions_admin.php
+++ b/phpBB/includes/functions_admin.php
@@ -814,11 +814,14 @@ function delete_attachments($mode, $ids, $resync = true)
 		return false;
 	}
 
+	$sql_where = '';
+
 	switch ($mode)
 	{
 		case 'post':
 		case 'message':
 			$sql_id = 'post_msg_id';
+			$sql_where = ' AND in_message = ' . ($mode == 'message' ? 1 : 0);
 		break;
 
 		case 'topic':
@@ -842,6 +845,9 @@ function delete_attachments($mode, $ids, $resync = true)
 	$sql = 'SELECT post_msg_id, topic_id, in_message, physical_filename, thumbnail, filesize, is_orphan
 			FROM ' . ATTACHMENTS_TABLE . '
 			WHERE ' . $db->sql_in_set($sql_id, $ids);
+
+	$sql .= $sql_where;
+
 	$result = $db->sql_query($sql);
 
 	while ($row = $db->sql_fetchrow($result))
@@ -867,6 +873,9 @@ function delete_attachments($mode, $ids, $resync = true)
 	// Delete attachments
 	$sql = 'DELETE FROM ' . ATTACHMENTS_TABLE . '
 		WHERE ' . $db->sql_in_set($sql_id, $ids);
+
+	$sql .= $sql_where;
+
 	$db->sql_query($sql);
 	$num_deleted = $db->sql_affectedrows();