diff --git a/src/Concerns/WithSteps.php b/src/Concerns/WithSteps.php
index 500c226..e2d5f96 100644
--- a/src/Concerns/WithSteps.php
+++ b/src/Concerns/WithSteps.php
@@ -82,7 +82,7 @@ public function validateStep($step = null, $setNext = true)
         $data = $this->customValidate($this->mapFields($resolvedFields, $this->store), $rules);
 
         if (! $this->model->id) {
-            $this->completedSteps[] = $step->name;
+            $this->completedSteps[] = optional($step)->name;
         }
 
         $step = $this->step($step);