diff --git a/src/Invoice/InvoiceFilename.php b/src/Invoice/InvoiceFilename.php
index b5612674..e20a7abf 100644
--- a/src/Invoice/InvoiceFilename.php
+++ b/src/Invoice/InvoiceFilename.php
@@ -30,8 +30,8 @@ final class InvoiceFilename
         }
 
         if (!empty($company)) {
-            $company = new UnicodeString($company);
-            $filename .= '-' . $company->snake();
+            $uCompany = new UnicodeString($company);
+            $filename .= '-' . $uCompany->ascii()->snake();
         }
 
         $this->filename = $filename;
diff --git a/tests/Invoice/InvoiceFilenameTest.php b/tests/Invoice/InvoiceFilenameTest.php
index d84f3b3d..f4eca948 100644
--- a/tests/Invoice/InvoiceFilenameTest.php
+++ b/tests/Invoice/InvoiceFilenameTest.php
@@ -47,7 +47,15 @@ class InvoiceFilenameTest extends TestCase
         $customer->setCompany('barß / laölala # ldksjf 123');
         $sut = new InvoiceFilename($model);
 
-        self::assertEquals($datePrefix . '-barß_laölala_ldksjf123', $sut->getFilename());
-        self::assertEquals($datePrefix . '-barß_laölala_ldksjf123', (string) $sut);
+        self::assertEquals($datePrefix . '-barss_laolala_ldksjf123', $sut->getFilename());
+        self::assertEquals($datePrefix . '-barss_laolala_ldksjf123', (string) $sut);
+
+        $customer->setCompany('까깨꺄꺠꺼께껴꼐꼬꽈sssss');
+        $sut = new InvoiceFilename($model);
+        self::assertEquals($datePrefix . '-kkakkaekkyakkyaekkeokkekkyeokkyekkokkwasssss', $sut->getFilename());
+
+        $customer->setCompany('\"#+ß.!$%&/()=?\\n=/*-+´_<>@' . "\n");
+        $sut = new InvoiceFilename($model);
+        self::assertEquals($datePrefix . '-ss_n', $sut->getFilename());
     }
 }