diff --git a/composer.json b/composer.json
index 7b9c933..7fc5e91 100644
--- a/composer.json
+++ b/composer.json
@@ -63,7 +63,7 @@
             "@composer run build",
             "@php vendor/bin/testbench serve"
         ],
-        "analyse": "vendor/bin/phpstan analyse",
+        "analyse": "vendor/bin/phpstan analyse --memory-limit 500M",
         "test": "vendor/bin/pest",
         "test-coverage": "vendor/bin/pest --coverage",
         "format": "vendor/bin/pint",
diff --git a/src/Invoice.php b/src/Invoice.php
index 58cb72c..ee90c6f 100644
--- a/src/Invoice.php
+++ b/src/Invoice.php
@@ -163,11 +163,14 @@ public function credit(): HasOne
      */
     public function getPreviousInvoice(): ?static
     {
-        return static::query()
+        /** @var ?static $invoice */
+        $invoice = static::query()
             ->when($this->getSerialNumberPrefix(), fn (Builder $query) => $query->where('serial_number_details->prefix', $this->getSerialNumberPrefix()))
             ->when($this->getSerialNumberSerie(), fn (Builder $query) => $query->where('serial_number_details->serie', $this->getSerialNumberSerie()))
             ->latest('serial_number')
             ->first();
+
+        return $invoice;
     }
 
     public function initSerialNumberDetailst(): static