diff --git a/lib/classes/dataformat/spout_base.php b/lib/classes/dataformat/spout_base.php
index 434b18c..c061f70 100644
--- a/lib/classes/dataformat/spout_base.php
+++ b/lib/classes/dataformat/spout_base.php
@@ -44,6 +44,13 @@ abstract class spout_base extends \core\dataformat\base {
     /** @var $sheettitle */
     protected $sheettitle;
 
+    /** Set proper encoding for mbstring. **/
+    public function __construct() {
+        if (extension_loaded('mbstring')) {
+            mb_internal_encoding('UTF-8');
+        }
+    }
+
     /**
      * Output file headers to initialise the download of the file.
      */