diff --git a/src/fields/Assets.php b/src/fields/Assets.php
index 966b5697..4b0d8c17 100644
--- a/src/fields/Assets.php
+++ b/src/fields/Assets.php
@@ -24,7 +24,7 @@
  */
 class Assets extends Field implements FieldInterface
 {
-    const EVENT_ASSET_FILENAME = 'onAssetFilename';
+    public const EVENT_ASSET_FILENAME = 'onAssetFilename';
 
     // Properties
     // =========================================================================