diff --git a/lib/Data.php b/lib/Data.php
index 2b6a33ff7..23be17f10 100755
--- a/lib/Data.php
+++ b/lib/Data.php
@@ -480,8 +480,8 @@ public function getActivitySince(string $user, int $since, bool $byOthers) {
 	 * @return void
 	 */
 	private function deleteActivitiesForMySQL(array $conditions): void {
-		$subQuery = $this->connection->getQueryBuilder();
-		$subQuery->select('activity_id')
+		$query = $this->connection->getQueryBuilder();
+		$query->select('activity_id')
 			->from('activity');
 
 		foreach ($conditions as $column => $comparison) {
@@ -492,11 +492,11 @@ private function deleteActivitiesForMySQL(array $conditions): void {
 				$operation = '=';
 				$value = $comparison;
 			}
-			$subQuery->where($subQuery->expr()->comparison($column, $operation, $subQuery->createNamedParameter($value)));
+			$query->where($query->expr()->comparison($column, $operation, $query->createNamedParameter($value)));
 		}
 
-		$subQuery->setMaxResults(10000);
-		$result = $subQuery->executeQuery();
+		$query->setMaxResults(10000);
+		$result = $query->executeQuery();
 		$count = $result->rowCount();
 		if($count === 0) {
 			return;
@@ -508,8 +508,8 @@ private function deleteActivitiesForMySQL(array $conditions): void {
 
 		$deleteQuery = $this->connection->getQueryBuilder();
 		$deleteQuery->delete('activity');
-		$deleteQuery->where($deleteQuery->expr()->in('activity_id', $deleteQuery->createParameter('ids'), IQueryBuilder::PARAM_STR_ARRAY));
-		$deleteQuery->setParameter('ids', $ids, IQueryBuilder::PARAM_STR_ARRAY);
+		$deleteQuery->where($deleteQuery->expr()->in('activity_id', $deleteQuery->createParameter('ids'), IQueryBuilder::PARAM_INT_ARRAY));
+		$deleteQuery->setParameter('ids', $ids, IQueryBuilder::PARAM_INT_ARRAY);
 		$queryResult = $deleteQuery->executeStatement();
 		if($queryResult === 10000) {
 			$this->deleteActivitiesForMySQL($conditions);