diff --git a/lms/djangoapps/instructor/views/legacy.py b/lms/djangoapps/instructor/views/legacy.py
index dad6378d4b..53c28793a5 100644
--- a/lms/djangoapps/instructor/views/legacy.py
+++ b/lms/djangoapps/instructor/views/legacy.py
@@ -694,7 +694,7 @@ def instructor_dashboard(request, course_id):
 
         datatable = {'header': ['User ID', 'Anonymized user ID', 'Course Specific Anonymized user ID']}
         datatable['data'] = [[s.id, unique_id_for_user(s), anonymous_id_for_user(s, course_id)] for s in students]
-        return return_csv(course_id.to_deprecated_string().replace('/', '-') + '-anon-ids.csv', datatable)
+        return return_csv(course_key.to_deprecated_string().replace('/', '-') + '-anon-ids.csv', datatable)
 
     #----------------------------------------
     # Group management