diff --git a/lib/editor/popups/insert_image.php b/lib/editor/popups/insert_image.php
index dcaedd8975d..1594ebe8d5d 100644
--- a/lib/editor/popups/insert_image.php
+++ b/lib/editor/popups/insert_image.php
@@ -10,7 +10,7 @@
 
 <head>
   <title>Insert Image</title>
-<meta http-equiv="content-type" content="text/html; charset=utf-8" />
+<meta http-equiv="content-type" content="text/html; <?php print_string("thischarset");?>" />
 <script type="text/javascript" src="popup.js"></script>
 
 <script type="text/javascript">
