diff --git a/lib/adminlib.php b/lib/adminlib.php
index 2efe8a81e4a..3edd526eea5 100644
--- a/lib/adminlib.php
+++ b/lib/adminlib.php
@@ -4942,14 +4942,18 @@ function print_plugin_tables() {
     $installed_mods = get_records_list('modules', '', '', '', 'name');
     $installed_blocks = get_records_list('block', '', '', '', 'name');
 
+    $plugins_installed['mod'] = array();
     foreach($installed_mods as $mod) {
         $plugins_installed['mod'][] = $mod->name;
     }
 
+    $plugins_installed['blocks'] = array();
     foreach($installed_blocks as $block) {
         $plugins_installed['blocks'][] = $block->name;
     }
 
+    $plugins_installed['filter'] = array();
+
     $plugins_ondisk = array();
     $plugins_ondisk['mod'] = get_list_of_plugins('mod', 'db');
     $plugins_ondisk['blocks'] = get_list_of_plugins('blocks', 'db');