diff --git a/.ci/phpstan.neon b/.ci/phpstan.neon
index 28575d40f0..5ae356250a 100644
--- a/.ci/phpstan.neon
+++ b/.ci/phpstan.neon
@@ -56,5 +56,5 @@ parameters:
 
   # The level 8 is the highest level. original was 5
   # TODO: slowly up the level and fix the issues found.
-  level: 5
+  level: 6