diff --git a/course/view.php b/course/view.php
index 1d330cf7b56..a332faca308 100644
--- a/course/view.php
+++ b/course/view.php
@@ -29,6 +29,7 @@
 
     add_to_log($course->id, "course", "view", "view.php?id=$course->id", "$course->id");
 
+    $course->format = clean_param($course->format, PARAM_ALPHA);
     if (!file_exists($CFG->dirroot.'/course/format/'.$course->format.'/format.php')) {
         $course->format = 'weeks';  // Default format is weeks
     }