diff --git a/system/core/Common.php b/system/core/Common.php
index 258cd49..136dd52 100644
--- a/system/core/Common.php
+++ b/system/core/Common.php
@@ -343,7 +343,7 @@
 	 */
 	function is_https()
 	{
-		return ( ! empty($_SERVER['HTTPS']) && strtolower($_SERVER['HTTPS']) !== 'off');
+		return (isset($_SERVER['HTTPS']) && strtolower($_SERVER['HTTPS']) === 'on');
 	}
 }
 
@@ -713,4 +713,4 @@
 }
 
 /* End of file Common.php */
-/* Location: ./system/core/Common.php */
\ No newline at end of file
+/* Location: ./system/core/Common.php */