diff --git a/phpBB/admin/page_header_admin.php b/phpBB/admin/page_header_admin.php
index 3195f461a2..b761b4b86a 100644
--- a/phpBB/admin/page_header_admin.php
+++ b/phpBB/admin/page_header_admin.php
@@ -35,7 +35,7 @@ if ( $board_config['gzip_compress'] )
 {
 	$phpver = phpversion();
 
-	$useragent = (isset($_SERVER["HTTP_USER_AGENT"]) ) ? $_SERVER["HTTP_USER_AGENT"] : $HTTP_USER_AGENT;
+	$useragent = (isset($HTTP_SERVER_VARS['HTTP_USER_AGENT'])) ? $HTTP_SERVER_VARS['HTTP_USER_AGENT'] : getenv('HTTP_USER_AGENT');
 
 	if ( $phpver >= '4.0.4pl1' && ( strstr($useragent,'compatible') || strstr($useragent,'Gecko') ) )
 	{
diff --git a/phpBB/includes/page_header.php b/phpBB/includes/page_header.php
index a65ae249bb..12676e1079 100644
--- a/phpBB/includes/page_header.php
+++ b/phpBB/includes/page_header.php
@@ -35,7 +35,7 @@ if ( $board_config['gzip_compress'] )
 {
 	$phpver = phpversion();
 
-	$useragent = (isset($_SERVER["HTTP_USER_AGENT"]) ) ? $_SERVER["HTTP_USER_AGENT"] : $HTTP_USER_AGENT;
+	$useragent = (isset($HTTP_SERVER_VARS['HTTP_USER_AGENT'])) ? $HTTP_SERVER_VARS['HTTP_USER_AGENT'] : getenv('HTTP_USER_AGENT');
 
 	if ( $phpver >= '4.0.4pl1' && ( strstr($useragent,'compatible') || strstr($useragent,'Gecko') ) )
 	{
@@ -466,7 +466,7 @@ else
 
 // Work around for "current" Apache 2 + PHP module which seems to not
 // cope with private cache control setting
-if (!empty($_SERVER['SERVER_SOFTWARE']) && strstr($_SERVER['SERVER_SOFTWARE'], 'Apache/2'))
+if (!empty($HTTP_SERVER_VARS['SERVER_SOFTWARE']) && strstr($HTTP_SERVER_VARS['SERVER_SOFTWARE'], 'Apache/2'))
 {
 	header ('Cache-Control: no-cache, pre-check=0, post-check=0');
 }