diff --git a/functions/strings.php b/functions/strings.php
index 84353fd5b..0180871f7 100644
--- a/functions/strings.php
+++ b/functions/strings.php
@@ -241,7 +241,7 @@
 
       // check for HTTPS mode (you must have 'SSLOptions +StdEnvVars'
       // in your apache config).
-      $HTTPS=getenv(HTTPS); 
+      $HTTPS=getenv('HTTPS');
 
       // Get the path
       $path = substr($PHP_SELF, 0, strrpos($PHP_SELF, '/'));