diff --git a/src/PostTypeManager.php b/src/PostTypeManager.php
index 9a27ef3..7752c13 100644
--- a/src/PostTypeManager.php
+++ b/src/PostTypeManager.php
@@ -99,7 +99,7 @@ public function registerPostTypes($classNames)
                     }
                 }
             }
-        }, '99', 2); // use high priority value to ensure this happens after acf finishes saving its metadata
+        }, 99, 2); // use high priority value to ensure this happens after acf finishes saving its metadata
 
         $this->registered = true;
         do_action('oowp/all_post_types_registered', $this->postTypes);