diff --git a/Application/Model/AbstractClasses/pdfdocumentsGeneric.php b/Application/Model/AbstractClasses/pdfdocumentsGeneric.php
index dbb7a54..867d61a 100644
--- a/Application/Model/AbstractClasses/pdfdocumentsGeneric.php
+++ b/Application/Model/AbstractClasses/pdfdocumentsGeneric.php
@@ -199,10 +199,18 @@ abstract class pdfdocumentsGeneric extends Base implements genericInterface
     {
         // forced filename from setFilename()
         if ($this->filename) {
-            return $this->addFilenameExtension($this->filename);
+            return $this->addFilenameExtension(
+                $this->makeValidFileName(
+                    $this->filename
+                )
+            );
         }
 
-        return $this->addFilenameExtension($this->getTypeForFilename());
+        return $this->addFilenameExtension(
+            $this->makeValidFileName(
+                $this->getTypeForFilename()
+            )
+        );
     }
 
     /**
diff --git a/Application/Model/AbstractClasses/pdfdocumentsOrder.php b/Application/Model/AbstractClasses/pdfdocumentsOrder.php
index cefd14d..3029148 100644
--- a/Application/Model/AbstractClasses/pdfdocumentsOrder.php
+++ b/Application/Model/AbstractClasses/pdfdocumentsOrder.php
@@ -69,19 +69,25 @@ abstract class pdfdocumentsOrder extends pdfdocumentsGeneric implements orderInt
     {
         // forced filename from setFilename()
         if ($this->filename) {
-            return $this->addFilenameExtension($this->filename);
+            return $this->addFilenameExtension(
+                $this->makeValidFileName(
+                    $this->filename
+                )
+            );
         }
 
         $sTrimmedBillName = trim($this->getOrder()->getFieldData('oxbilllname'));
 
         return $this->addFilenameExtension(
-            implode(
-                '_',
-                [
-                    $this->getTypeForFilename(),
-                    $this->getOrder()->getFieldData('oxordernr'),
-                    $sTrimmedBillName
-                ]
+            $this->makeValidFileName(
+                implode(
+                    '_',
+                    [
+                        $this->getTypeForFilename(),
+                        $this->getOrder()->getFieldData('oxordernr'),
+                        $sTrimmedBillName
+                    ]
+                )
             )
         );
     }
diff --git a/Application/Model/Documents/invoicePdf.php b/Application/Model/Documents/invoicePdf.php
index 4a7edaf..1761067 100644
--- a/Application/Model/Documents/invoicePdf.php
+++ b/Application/Model/Documents/invoicePdf.php
@@ -111,10 +111,12 @@ class invoicePdf extends pdfdocumentsOrder implements pdfdocumentsOrderinvoiceIn
     {
         $filename = parent::getFilename();
 
-        return str_replace(
+        $filename = str_replace(
             $this->getOrder()->getFieldData('oxordernr'),
             $this->getOrder()->getFieldData('oxbillnr'),
             $filename
         );
+
+        return $this->makeValidFileName($filename);
     }
 }
\ No newline at end of file