diff --git a/src/MailHog.php b/src/MailHog.php
index acbfc36..9920251 100644
--- a/src/MailHog.php
+++ b/src/MailHog.php
@@ -444,7 +444,7 @@ protected function getDecodedEmailProperty($email, $property) {
       ) {
           $property = quoted_printable_decode($property);
       }
-      if (strpos($property, '=?utf-8?Q?') !== false && extension_loaded('mbstring')) {
+      if (stripos($property, '=?utf-8?Q?') !== false && extension_loaded('mbstring')) {
         $property = mb_decode_mimeheader($property);
       }
     }