diff --git a/includes/libraries/class-emogrifier.php b/includes/libraries/class-emogrifier.php
index 97ed1d34dd7..687dc10ec71 100644
--- a/includes/libraries/class-emogrifier.php
+++ b/includes/libraries/class-emogrifier.php
@@ -352,7 +352,8 @@ class Emogrifier {
         $this->copyCssWithMediaToStyleNode($cssParts, $xmlDocument);
 
         if ($this->preserveEncoding) {
-            return mb_convert_encoding($xmlDocument->saveHTML(), self::ENCODING, 'HTML-ENTITIES');
+            if ( function_exists('mb_convert_encoding') ) { return mb_convert_encoding($xmlDocument->saveHTML(), self::ENCODING, 'HTML-ENTITIES'); }
+            else { return $xmlDocument->saveHTML(); }
         } else {
             return $xmlDocument->saveHTML();
         }
@@ -536,7 +537,8 @@ class Emogrifier {
             $bodyWithoutUnprocessableTags = $this->html;
         }
 
-        return mb_convert_encoding($bodyWithoutUnprocessableTags, 'HTML-ENTITIES', self::ENCODING);
+        if ( function_exists('mb_convert_encoding') ) { return mb_convert_encoding($bodyWithoutUnprocessableTags, 'HTML-ENTITIES', self::ENCODING); }
+        else { return $bodyWithoutUnprocessableTags; }
     }
 
     /**