diff --git a/extensions/tags/src/TagCountValidator.php b/extensions/tags/src/TagCountValidator.php
index 5a72d019dc..52b75a67f2 100644
--- a/extensions/tags/src/TagCountValidator.php
+++ b/extensions/tags/src/TagCountValidator.php
@@ -97,10 +97,10 @@ protected function getRules()
             ]
         ];
 
-        if ( $min === $max ) {
-            Arr::add($rules, $key, "size:{$min}");
+        if ($min === $max) {
+            $rules[$key][] = "size:{$min}";
         } else {
-            Arr::add($rules, $key, "between:{$min},{$max}");
+            $rules[$key][] = "between:{$min},{$max}";
         }
 
         return $rules;