diff --git a/shard.yml b/shard.yml
index 9a2e409..bf6944c 100644
--- a/shard.yml
+++ b/shard.yml
@@ -1,5 +1,5 @@
 name: office365
-version: 1.20.1
+version: 1.21.0
 
 crystal: ">= 0.36.1"
 
diff --git a/src/models/recurrence_param.cr b/src/models/recurrence_param.cr
index c4e47d6..ff63878 100644
--- a/src/models/recurrence_param.cr
+++ b/src/models/recurrence_param.cr
@@ -1,12 +1,15 @@
+require "./recurrence_pattern"
+
 module Office365
   class RecurrenceParam
     property pattern : String
     property range_end : Time
     property interval : Int32?
+    property index : WeekIndex?
     property days_of_week : Array(String)
     property first_day_of_week : Office365::DayOfWeek?
 
-    def initialize(@pattern : String, @range_end : Time, @interval : Int32? = 1, @days_of_week : Array(String) = [] of String, first_day_of_week : String? = nil)
+    def initialize(@pattern : String, @range_end : Time, @interval : Int32? = 1, @days_of_week : Array(String) = [] of String, first_day_of_week : String? = nil, @index : WeekIndex? = nil)
       @first_day_of_week = first_day_of_week ? Office365::DayOfWeek.parse(first_day_of_week) : Office365::DayOfWeek::Sunday
     end
   end