diff --git a/tests/vufind.php_cs b/tests/vufind.php_cs
index a5f7e3f6975a056d9add81466d5943363188d2a5..6cac4596895d0f69f9aabc9723d2be97a37af3cf 100644
--- a/tests/vufind.php_cs
+++ b/tests/vufind.php_cs
@@ -56,6 +56,7 @@ $rules = [
     'no_useless_return' => true,
     'no_whitespace_before_comma_in_array' => true,
     'no_whitespace_in_blank_line' => true,
+    'non_printable_character' => true,
     'ordered_imports' => true,
     'phpdoc_no_access' => true,
     'single_blank_line_at_eof' => true,
diff --git a/tests/vufind_templates.php_cs b/tests/vufind_templates.php_cs
index c45246684394e2d7c7c3942efd66c82a0a121e93..6db30f69c9f7837d5f51fef6f3b568e6b9266bdb 100644
--- a/tests/vufind_templates.php_cs
+++ b/tests/vufind_templates.php_cs
@@ -50,6 +50,7 @@ $rules = [
     'no_useless_return' => true,
     'no_whitespace_before_comma_in_array' => true,
     'no_whitespace_in_blank_line' => true,
+    'non_printable_character' => true,
     'ordered_imports' => true,
     'phpdoc_no_access' => true,
     'single_blank_line_at_eof' => true,