diff --git a/scripts/gpgcerts.php b/scripts/gpgcerts.php
index 43537ec..84c9eab 100755
--- a/scripts/gpgcerts.php
+++ b/scripts/gpgcerts.php
@@ -15,6 +15,10 @@
 */
 	include_once("../includes/mysql.php");
 
+        $lck = fopen('/tmp/GPGlock', 'w');
+        while(flock($lck, LOCK_EX) < 0)
+                sleep(rand(100000,200000));
+
 	$query = "select * from `gpg` where `crt`=''";
 	$res = mysql_query($query);
 	while($row = mysql_fetch_assoc($res))
@@ -62,4 +66,7 @@
 			mysql_query($query);
 		}
 	}
+
+        flock($lck, LOCK_UN);
+        fclose($lck);
 ?>