diff --git a/functions.php b/functions.php
index 163b4adda..116082988 100644
--- a/functions.php
+++ b/functions.php
@@ -1720,17 +1720,19 @@
 	}
 
 	function file_is_locked($filename) {
-		error_reporting(0);
-		$fp = fopen($filename, "r");
-		error_reporting(DEFAULT_ERROR_LEVEL);
-		if ($fp) {
-			if (flock($fp, LOCK_EX | LOCK_NB)) {
-				flock($fp, LOCK_UN);
+		if (function_exists('flock')) {
+			error_reporting(0);
+			$fp = fopen($filename, "r");
+			error_reporting(DEFAULT_ERROR_LEVEL);
+			if ($fp) {
+				if (flock($fp, LOCK_EX | LOCK_NB)) {
+					flock($fp, LOCK_UN);
+					fclose($fp);
+					return false;
+				}
 				fclose($fp);
-				return false;
+				return true;
 			}
-			fclose($fp);
-			return true;
 		}
 		return false;
 	}
diff --git a/update_feeds.php b/update_feeds.php
index d06beb829..967d2e429 100644
--- a/update_feeds.php
+++ b/update_feeds.php
@@ -12,7 +12,15 @@
 	require_once "db.php";
 	require_once "db-prefs.php";
 	require_once "functions.php";
-	require_once "magpierss/rss_fetch.inc";
+
+	$lock_filename = "update_feeds.lock";
+
+	$lock_handle = make_lockfile($lock_filename);
+
+	if (!$lock_handle) {
+		die("error: Can't create lockfile ($lock_filename). ".
+			"Maybe another process is already running.\n");
+	}
 
 	$link = db_connect(DB_HOST, DB_USER, DB_PASS, DB_NAME);	
 
@@ -46,4 +54,5 @@
 
 	db_close($link);
 
+	unlink($lock_filename);
 ?>