diff --git a/html/inc/util.inc b/html/inc/util.inc
index 4bddd85834..5ac832619d 100644
--- a/html/inc/util.inc
+++ b/html/inc/util.inc
@@ -462,7 +462,8 @@ function post_int($name, $optional=false) {
 }
 
 function get_str($name, $optional=false) {
-    $x = $_GET[$name];
+    $x = null;
+    if (isset($_GET[$name])) $x = $_GET[$name];
     if (!$x && !$optional) {
         error_page("missing or bad parameter: $name");
     }