diff --git a/system/ee/ExpressionEngine/Service/Filter/Filter.php b/system/ee/ExpressionEngine/Service/Filter/Filter.php
index 428abe3800..468af6af86 100644
--- a/system/ee/ExpressionEngine/Service/Filter/Filter.php
+++ b/system/ee/ExpressionEngine/Service/Filter/Filter.php
@@ -58,7 +58,7 @@ abstract class Filter
     /**
      * @var string The value to use for the custom input's placeholder="" attribute
      */
-    protected $placeholder;
+    protected $placeholder = '';
 
     /**
      * @var bool Whether or not this filter has a custom <input> element