diff --git a/src/Invoice.php b/src/Invoice.php
index 9364528..cfed2e3 100644
--- a/src/Invoice.php
+++ b/src/Invoice.php
@@ -244,7 +244,7 @@ public function getSerialNumberPrefixFromConfig(string $default = ''): string
             return $prefixes;
         }
 
-        return data_get($prefixes, $this->type?->value, $default);
+        return data_get($prefixes, $this->type->value, $default);
     }
 
     public function getSerialNumberPrefix(): ?string