diff --git a/modules/node/node.module b/modules/node/node.module
index 4cc6bdf..e88444a 100644
--- a/modules/node/node.module
+++ b/modules/node/node.module
@@ -2256,11 +2256,20 @@ function node_access_acquire_grants($node) {
  */
 function node_access_write_grants($node, $grants, $realm = NULL, $delete = TRUE) {
   if ($delete) {
-    $query = 'DELETE FROM {node_access} WHERE nid = %d';
-    if ($realm) {
-      $query .= " AND realm in ('%s', 'all')";
+    // Prevent deletion of node access table entries if node id is not existing.
+    // Otherwise the node id will be interpreted as 0 wiping out access for all
+    // anonymous users, see http://drupal.org/node/282555.
+    if (empty($node->nid) || !intval($node->nid)) {
+      $url = url($_REQUEST['q'], array('absolute' => TRUE));
+      watchdog('node', 'Node access grants for node @title couldn\'t be wiped out as node id is not existing.', array('@title' => $node->title), WATCHDOG_ERROR, $url);
+    }
+    else {
+      $query = 'DELETE FROM {node_access} WHERE nid = %d';
+      if ($realm) {
+        $query .= " AND realm in ('%s', 'all')";
+      }
+      db_query($query, $node->nid, $realm);
     }
-    db_query($query, $node->nid, $realm);
   }
 
   // Only perform work when node_access modules are active.