diff --git a/src/Listeners/SubscriptionChargeCompleted.php b/src/Listeners/SubscriptionChargeCompleted.php
index 86f1db8..45fc4f9 100644
--- a/src/Listeners/SubscriptionChargeCompleted.php
+++ b/src/Listeners/SubscriptionChargeCompleted.php
@@ -6,6 +6,7 @@
 use TwentyTwoDigital\CashierFastspring\Invoice;
 use TwentyTwoDigital\CashierFastspring\Subscription;
 use Carbon\Carbon;
+use Illuminate\Support\Str;
 
 /**
  * This class is a listener for subscription charge completed events.
@@ -55,7 +56,7 @@ public function handle(Events\SubscriptionChargeCompleted $event)
         $periodEndDate = $nextDate->subDay()->format('Y-m-d H:i:s');
 
         // yeap, weird way
-        $methodName = 'sub'.title_case($subscription->interval_unit).'sNoOverflow';
+        $methodName = 'sub'.Str::title($subscription->interval_unit).'sNoOverflow';
         $periodStartDate = $nextDate->$methodName($subscription->interval_length)->addDay()->format('Y-m-d H:i:s');
 
         // fill the model