diff --git a/app/Services/Registries/CleanerService.php b/app/Services/Registries/CleanerService.php
index e08a2d9..3366245 100644
--- a/app/Services/Registries/CleanerService.php
+++ b/app/Services/Registries/CleanerService.php
@@ -30,11 +30,14 @@ class CleanerService {
     }
 
 
-    public function cleanString(string $string): string {
-        $string = Str::replace('"', '"', $string);
-        $string = Str::replace('&#40', '«', $string);
-        $string = Str::replace('&#41', '»', $string);
-        return trim(Str::replace('(***)', '', $string));
+    public function cleanString(?string $string): ?string {
+        if ($string) {
+            $string = Str::replace('"', '"', $string);
+            $string = Str::replace('&#40', '«', $string);
+            $string = Str::replace('&#41', '»', $string);
+            $string = trim(Str::replace('(***)', '', $string));
+        }
+        return $string;
     }
 
 }
\ No newline at end of file