--- a/feedback.php
+++ b/feedback.php
@@ -31,7 +31,7 @@
 } else {
 $stopid = "";
 $stopcode = "";
-$urlparts = explode("?",$_SERVER["HTTP_REFERER"]);
+if (isset($_SERVER["HTTP_REFERER"])) $urlparts = explode("?",$_SERVER["HTTP_REFERER"]);
 if (isset($urlparts[1])) {
     $getparams = explode("&",$urlparts[1]);
     foreach ($getparams as $param) {
@@ -60,7 +60,7 @@
 </textarea>
 <textarea name="extrainfo" id="extrainfo">
 <?php
-  echo "Referrer URL: ".$_SERVER["HTTP_REFERER"];
+  echo "Referrer URL: ".($_SERVER["HTTP_REFERER"] ? $_SERVER["HTTP_REFERER"] : "");
   echo "\nCurrent page URL: ".curPageURL();
   echo "\nUser Agent: ".$_SERVER["HTTP_USER_AGENT"];
   echo "\nUser host/IP: ".$_SERVER["HTTP_X_FORWARDED_FOR"]." ".$_SERVER["REMOTE_ADDR"]; 

--- a/include/common-template.inc.php
+++ b/include/common-template.inc.php
@@ -27,7 +27,7 @@
     $url.= $GA_PIXEL . "?";
     $url.= "utmac=" . $GA_ACCOUNT;
     $url.= "&utmn=" . rand(0, 0x7fffffff);
-    $referer = $_SERVER["HTTP_REFERER"];
+    $referer = (isset($_SERVER["HTTP_REFERER"]) ? $_SERVER["HTTP_REFERER"] : "");
     $query = $_SERVER["QUERY_STRING"];
     $path = $_SERVER["REQUEST_URI"];
     if (empty($referer)) {