diff --git a/src/Bundle/ChillTaskBundle/Repository/SingleTaskAclAwareRepository.php b/src/Bundle/ChillTaskBundle/Repository/SingleTaskAclAwareRepository.php
index d1652cc89..53ed4c38d 100644
--- a/src/Bundle/ChillTaskBundle/Repository/SingleTaskAclAwareRepository.php
+++ b/src/Bundle/ChillTaskBundle/Repository/SingleTaskAclAwareRepository.php
@@ -58,12 +58,12 @@ final class SingleTaskAclAwareRepository implements SingleTaskAclAwareRepository
         $qb
             ->from(SingleTask::class, 't');
 
-        if (!empty($pattern)) {
+        if (null !== $pattern && '' !== $pattern) {
             $qb->andWhere($qb->expr()->like('LOWER(UNACCENT(t.title))', 'LOWER(UNACCENT(:pattern))'))
                 ->setParameter('pattern', '%' . $pattern . '%');
         }
 
-        if (count($users) > 0) {
+        if (null !== $users && count($users) > 0) {
             $orXUser = $qb->expr()->orX();
 
             foreach ($users as $key => $user) {
@@ -81,7 +81,7 @@ final class SingleTaskAclAwareRepository implements SingleTaskAclAwareRepository
             return $qb;
         }
 
-        if (count($flags) > 0) {
+        if (null !== $flags && count($flags) > 0) {
             $orXDate = $qb->expr()->orX();
             $orXState = $qb->expr()->orX();
             $now = new DateTime();