diff --git a/core/Mail.php b/core/Mail.php
index 192c5a94e5c2416e5d3d3ab3cf3a9cf2944a2dd6..c6c8623cfd279740b9afcc7c9638e739f52a4df4 100644
--- a/core/Mail.php
+++ b/core/Mail.php
@@ -129,13 +129,13 @@ class Mail extends Zend_Mail
 
     public function createAttachment($body, $mimeType = null, $disposition = null, $encoding = null, $filename = null)
     {
-        $filename = self::sanitiseString($filename);
+        $filename = $this->sanitiseString($filename);
         return parent::createAttachment($body, $mimeType, $disposition, $encoding, $filename);
     }
 
     public function setSubject($subject)
     {
-        $subject = self::sanitiseString($subject);
+        $subject = $this->sanitiseString($subject);
         return parent::setSubject($subject);
     }
 
@@ -173,7 +173,7 @@ class Mail extends Zend_Mail
      * @param $string
      * @return mixed
      */
-    static public function sanitiseString($string)
+    function sanitiseString($string)
     {
         $search = array('–', '’');
         $replace = array('-', '\'');
diff --git a/tests/PHPUnit/Integration/MailTest.php b/tests/PHPUnit/Integration/MailTest.php
index f112948a4228498f58d8d70747f71cc8e62d8b33..876804c52f69d13dc4b3d7db259195d589290473 100644
--- a/tests/PHPUnit/Integration/MailTest.php
+++ b/tests/PHPUnit/Integration/MailTest.php
@@ -26,6 +26,7 @@ class MailTest extends \PHPUnit_Framework_TestCase
      */
     public function test_EmailFilenamesAreSanitised($raw, $expected)
     {
-        $this->assertEquals($expected, Mail::sanitiseString($raw));
+        $mail = new Mail;
+        $this->assertEquals($expected, $mail->sanitiseString($raw));
     }
 }