diff --git a/phpBB/docs/CHANGELOG.html b/phpBB/docs/CHANGELOG.html
index 92e00b0a56..34e1964227 100644
--- a/phpBB/docs/CHANGELOG.html
+++ b/phpBB/docs/CHANGELOG.html
@@ -150,6 +150,7 @@
 		<li>[Fix] Disable word-censor option in UCP lacks the config-setting (Bug #47575 - Patch by 00mohgta7)</li>
 		<li>[Fix] Fix database updater and db tools to support multiple column changes/additions/removals with SQLite</li>
 		<li>[Fix] Fix cosmetic ACP bug showing on hover elements in IE7 (Bug #16109 - Patch by prototech)</li>
+		<li>[Fix] Correctly detect GZIP status in debug mode. (Bug #24075 - Patch by rxu)</li>
 		<li>[Change] Change the data format of the default file ACM to be more secure from tampering and have better performance.</li>
 		<li>[Change] Add index on log_time to the log table to prevent slowdown on boards with many log entries. (Bug #44665 - Patch by bantu)</li>
 		<li>[Change] Template engine now permits to a limited extent variable includes.</li>
diff --git a/phpBB/includes/acp/acp_main.php b/phpBB/includes/acp/acp_main.php
index e0d6a3f01c..f9d611f8db 100644
--- a/phpBB/includes/acp/acp_main.php
+++ b/phpBB/includes/acp/acp_main.php
@@ -485,7 +485,7 @@ class acp_main
 			'UPLOAD_DIR_SIZE'	=> $upload_dir_size,
 			'TOTAL_ORPHAN'		=> $total_orphan,
 			'S_TOTAL_ORPHAN'	=> ($total_orphan === false) ? false : true,
-			'GZIP_COMPRESSION'	=> ($config['gzip_compress']) ? $user->lang['ON'] : $user->lang['OFF'],
+			'GZIP_COMPRESSION'	=> ($config['gzip_compress'] && @extension_loaded('zlib')) ? $user->lang['ON'] : $user->lang['OFF'],
 			'DATABASE_INFO'		=> $db->sql_server_info(),
 			'BOARD_VERSION'		=> $config['version'],
 
diff --git a/phpBB/includes/functions.php b/phpBB/includes/functions.php
index c6f6084918..60fe6a454f 100644
--- a/phpBB/includes/functions.php
+++ b/phpBB/includes/functions.php
@@ -3927,7 +3927,7 @@ function page_footer($run_cron = true)
 			$db->sql_report('display');
 		}
 
-		$debug_output = sprintf('Time : %.3fs | ' . $db->sql_num_queries() . ' Queries | GZIP : ' . (($config['gzip_compress']) ? 'On' : 'Off') . (($user->load) ? ' | Load : ' . $user->load : ''), $totaltime);
+		$debug_output = sprintf('Time : %.3fs | ' . $db->sql_num_queries() . ' Queries | GZIP : ' . (($config['gzip_compress'] && @extension_loaded('zlib')) ? 'On' : 'Off') . (($user->load) ? ' | Load : ' . $user->load : ''), $totaltime);
 
 		if ($auth->acl_get('a_') && defined('DEBUG_EXTRA'))
 		{
diff --git a/phpBB/language/en/acp/board.php b/phpBB/language/en/acp/board.php
index 9247a87e52..0ac7d1fb6b 100644
--- a/phpBB/language/en/acp/board.php
+++ b/phpBB/language/en/acp/board.php
@@ -394,7 +394,7 @@ $lang = array_merge($lang, array(
 	'ACP_SERVER_SETTINGS_EXPLAIN'	=> 'Here you define server and domain dependant settings. Please ensure the data you enter is accurate, errors will result in e-mails containing incorrect information. When entering the domain name remember it does include http:// or other protocol term. Only alter the port number if you know your server uses a different value, port 80 is correct in most cases.',
 
 	'ENABLE_GZIP'				=> 'Enable GZip compression',
-	'ENABLE_GZIP_EXPLAIN'		=> 'Generated content will be compressed prior to sending it to the user. This can reduce network traffic but will also increase CPU usage on both server and client side.',
+	'ENABLE_GZIP_EXPLAIN'		=> 'Generated content will be compressed prior to sending it to the user. This can reduce network traffic but will also increase CPU usage on both server and client side. Requires zlib PHP extension to be loaded.',
 	'FORCE_SERVER_VARS'			=> 'Force server URL settings',
 	'FORCE_SERVER_VARS_EXPLAIN'	=> 'If set to yes the server settings defined here will be used in favour of the automatically determined values.',
 	'ICONS_PATH'				=> 'Post icons storage path',