diff --git a/config/config.ini.php b/config/config.ini.php
index ea3df52cbd..a324e709ec 100644
--- a/config/config.ini.php
+++ b/config/config.ini.php
@@ -121,9 +121,14 @@ db_loglimit_index_high = 0
 
 ; dbclean_expire_conversation (Integer)
 ; When DBClean is enabled, any entry in the conversation table will be deleted after this many days.
-; These data are normally needed only for debugging purposes and they are safe to delete.
+: This data is used for ActivityPub, so it shouldn't be lower than the average duration of a discussion.
 dbclean_expire_conversation = 90
 
+; dbclean-expire-limit (Integer)
+; This defines the number of items that are to be deleted in a single call.
+; Reduce this value when you are getting memory issues.
+dbclean-expire-limit = 1000
+
 ; diaspora_test (Boolean)
 ; For development only. Disables the message transfer.
 diaspora_test = false
diff --git a/src/Worker/DBClean.php b/src/Worker/DBClean.php
index ca0da954c0..dba9cfd4c6 100644
--- a/src/Worker/DBClean.php
+++ b/src/Worker/DBClean.php
@@ -63,7 +63,7 @@ class DBClean {
 		$count = 0;
 
 		// We split the deletion in many small tasks
-		$limit = 1000;
+		$limit = Config::get('system', 'dbclean-expire-limit', 1000);
 
 		// Get the expire days for step 8 and 9
 		$days = Config::get('system', 'dbclean-expire-days', 0);
@@ -275,7 +275,7 @@ class DBClean {
 	                                                                OR (`item`.`file` != '') OR (`item`.`event-id` != '')
 	                                                                OR (`item`.`attach` != '') OR `item`.`wall` OR `item`.`origin`)
 	                                                                AND `item`.`parent` = `thread`.`iid`)
-	                                ORDER BY `thread`.`iid` LIMIT 1000", $days, $last_id);
+	                                ORDER BY `thread`.`iid` LIMIT ?", $days, $last_id, $limit);
 			$count = DBA::numRows($r);
 			if ($count > 0) {
 				logger("found expired threads: ".$count);