diff --git a/SeedDMS_Core/Core/inc.ClassDocument.php b/SeedDMS_Core/Core/inc.ClassDocument.php
index 4da4abb17..c5e9bf660 100644
--- a/SeedDMS_Core/Core/inc.ClassDocument.php
+++ b/SeedDMS_Core/Core/inc.ClassDocument.php
@@ -1292,6 +1292,15 @@ class SeedDMS_Core_Document extends SeedDMS_Core_Object { /* {{{ */
 		if(!$user)
 			return M_NONE;
 
+		/* Check if 'onCheckAccessDocument' callback is set */
+		if(isset($this->_dms->callbacks['onCheckAccessDocument'])) {
+			foreach($this->_dms->callbacks['onCheckAccessDocument'] as $callback) {
+				if(($ret = call_user_func($callback[0], $callback[1], $this, $user)) > 0) {
+					return $ret;
+				}
+			}
+		}
+
 		/* Administrators have unrestricted access */
 		if ($user->isAdmin()) return M_ALL;