diff --git a/src/Forms/IconPicker.php b/src/Forms/IconPicker.php
index 98213e8..1c3414e 100644
--- a/src/Forms/IconPicker.php
+++ b/src/Forms/IconPicker.php
@@ -192,7 +192,7 @@ public function getOptionLabelFromRecordUsing(?Closure $callback): static
         throw new \BadMethodCallException('Method not allowed.');
     }
 
-    public function createOptionUsing(Closure $callback): static
+    public function createOptionUsing(?Closure $callback): static
     {
         throw new \BadMethodCallException('Method not allowed.');
     }