diff --git a/sharethis.module b/sharethis.module
index 647cdb5..7313da4 100644
--- a/sharethis.module
+++ b/sharethis.module
@@ -636,7 +636,8 @@ function sharethis_include_js() {
     drupal_add_js($st_js, 'inline');
 
     //$external = "//ws.sharethis.com/button/buttons.js";
-    $external = ((isset($_SERVER['HTTPS']) && strtolower($_SERVER['HTTPS']) == 'on') ? "https://ws." : "http://w.") . "sharethis.com/button/buttons.js";
+    $secure = (isset($_SERVER['HTTPS']) && strtolower($_SERVER['HTTPS']) == 'on') || (isset($_SERVER['HTTP_X_FORWARDED_PROTO']) && strtolower($_SERVER['HTTP_X_FORWARDED_PROTO']) == 'https');
+    $external = ($secure ? "https://ws." : "http://w.") . "sharethis.com/button/buttons.js";
     drupal_add_js($external, 'external');
 
     $stlight = get_stLight_options($data_options);