diff --git a/.php-cs-fixer.php b/.php-cs-fixer.php
index 78ffda6407..01bfc271df 100644
--- a/.php-cs-fixer.php
+++ b/.php-cs-fixer.php
@@ -35,6 +35,7 @@
             'style' => 'post',
         ],
         'indentation_type' => true,
+        'is_null' => true,
         'line_ending' => true,
         'new_with_parentheses' => true,
         'no_extra_blank_lines' => true,
diff --git a/include/layout.inc b/include/layout.inc
index 44fb31ddfa..356e009cc0 100644
--- a/include/layout.inc
+++ b/include/layout.inc
@@ -379,7 +379,7 @@ function print_news($news, $dog, $max = 5, $onlyyear = null, $return = false) {
         // Only print entries in the provided s/dog/cat/ egory
         // If $dog is null, everything matches
         foreach ($item["category"] as $category) {
-            if (is_null($dog) || in_array($category["term"], (array)$dog, true)) {
+            if (null === $dog || in_array($category["term"], (array)$dog, true)) {
                 $ok = true;
                 $count++;
                 break;