diff --git a/lib/Service/MailFilter/FilterBuilder.php b/lib/Service/MailFilter/FilterBuilder.php
index 5d0b2731c1..5b8673dc8d 100644
--- a/lib/Service/MailFilter/FilterBuilder.php
+++ b/lib/Service/MailFilter/FilterBuilder.php
@@ -58,6 +58,11 @@ public function buildSieveScript(array $filters, string $untouchedScript): strin
 				}
 			}
 
+			if (count($tests) === 0) {
+				// skip filter without tests
+				continue;
+			}
+
 			$actions = [];
 			foreach ($filter['actions'] as $action) {
 				if ($action['type'] === 'fileinto') {
@@ -82,8 +87,6 @@ public function buildSieveScript(array $filters, string $untouchedScript): strin
 				}
 			}
 
-			// Error: lib/Service/MailFilter/FilterBuilder.php:88:15: PossiblyUndefinedArrayOffset: Possibly undefined array key $tests[0] on list{0?: non-empty-string} (see https://psalm.dev/167)
-
 			if (count($tests) > 1) {
 				$ifTest = sprintf('%s (%s)', $filter['operator'], implode(', ', $tests));
 			} else {