diff --git a/calendar/externallib.php b/calendar/externallib.php
index baf793d3f2e..dae1756b118 100644
--- a/calendar/externallib.php
+++ b/calendar/externallib.php
@@ -1027,8 +1027,8 @@ class core_calendar_external extends external_api {
     public static function get_calendar_monthly_view_parameters() {
         return new external_function_parameters(
             [
-                'year' => new external_value(PARAM_INT, 'Month to be viewed', VALUE_REQUIRED),
-                'month' => new external_value(PARAM_INT, 'Year to be viewed', VALUE_REQUIRED),
+                'year' => new external_value(PARAM_INT, 'Year to be viewed', VALUE_REQUIRED),
+                'month' => new external_value(PARAM_INT, 'Month to be viewed', VALUE_REQUIRED),
                 'courseid' => new external_value(PARAM_INT, 'Course being viewed', VALUE_DEFAULT, SITEID, NULL_ALLOWED),
                 'categoryid' => new external_value(PARAM_INT, 'Category being viewed', VALUE_DEFAULT, null, NULL_ALLOWED),
                 'includenavigation' => new external_value(