diff --git a/backup/backuplib.php b/backup/backuplib.php
index 7a15b65f540..339a6fce8ac 100644
--- a/backup/backuplib.php
+++ b/backup/backuplib.php
@@ -9,7 +9,7 @@
         $status = true;
         $status = execute_sql("INSERT INTO {$CFG->prefix}backup_ids
                                    (backup_code, table_name, old_id)
-                               SELECT DISTINCT '$backup_unique_code','quiz_categories',t.category
+                               SELECT DISTINCT $backup_unique_code,'quiz_categories',t.category
                                FROM {$CFG->prefix}quiz_questions t,
                                     {$CFG->prefix}quiz_question_grades g,
                                     {$CFG->prefix}quiz q
diff --git a/lib/datalib.php b/lib/datalib.php
index bfadd99e7fd..dc575169366 100644
--- a/lib/datalib.php
+++ b/lib/datalib.php
@@ -2029,7 +2029,7 @@ function get_courses_page($categoryid="all", $sort="c.sortorder ASC", $fields="c
     global $USER, $CFG;
 
     $categoryselect = "";
-    if ($categoryid != "all") {
+    if ($categoryid != "all" && is_numeric($categoryid)) {
         $categoryselect = "c.category = '$categoryid'";
     }