diff --git a/discovery.php b/discovery.php
index e56f104bf6..e3a7366dd3 100755
--- a/discovery.php
+++ b/discovery.php
@@ -105,6 +105,13 @@ if ($config['distributed_poller'] === true) {
     $where .= ' AND poller_group IN('.$config['distributed_poller_group'].')';
 }
 
+echo 'Checking for MySQL Locks:';
+while (!dbCheckLock('schema_update')) {
+    echo '.';
+    sleep(1);
+}
+echo PHP_EOL;
+
 foreach (dbFetch("SELECT * FROM `devices` WHERE status = 1 AND disabled = 0 $where ORDER BY device_id DESC") as $device) {
     if (dbGetLock('discovering.' . $device['device_id'])) {
         discover_device($device, $options);
diff --git a/includes/sql-schema/update.php b/includes/sql-schema/update.php
index e3e5febd16..93fe7eb6bf 100644
--- a/includes/sql-schema/update.php
+++ b/includes/sql-schema/update.php
@@ -98,10 +98,6 @@ if (!dbGetLock('schema_update')) {
 
 register_shutdown_function('dbReleaseLock','schema_update');
 
-do {
-    sleep(1);
-} while (@dbFetchCell('SELECT COUNT(*) FROM `devices` WHERE NOT IS_FREE_LOCK(CONCAT("polling.", device_id)) OR NOT IS_FREE_LOCK(CONCAT("queued.", device_id)) OR NOT IS_FREE_LOCK(CONCAT("discovering.", device_id))') > 0);
-
 foreach ($filelist as $file) {
     list($filename,$extension) = explode('.', $file, 2);
     if ($filename > $db_rev) {
@@ -171,3 +167,5 @@ if ($updating) {
 
     echo "-- Done\n";
 }
+
+dbReleaseLock('schema_update');
diff --git a/poller.php b/poller.php
index 57132457d7..0440997c32 100755
--- a/poller.php
+++ b/poller.php
@@ -100,6 +100,13 @@ if (isset($options['r'])) {
     $config['norrd'] = true;
 }
 
+echo 'Checking for MySQL Locks:';
+while (!dbCheckLock('schema_update')) {
+    echo '.';
+    sleep(1);
+}
+echo PHP_EOL;
+
 rrdtool_pipe_open($rrd_process, $rrd_pipes);
 
 echo "Starting polling run:\n\n";