diff --git a/app/models/event.rb b/app/models/event.rb
index e8e8743..d1044b0 100644
--- a/app/models/event.rb
+++ b/app/models/event.rb
@@ -280,7 +280,9 @@ class Event
         end
         tmp_start_date = [start_date, @start_date].max
         @start_date += add_interval
-        @end_date += add_interval
+        if @end_date
+          @end_date += add_interval
+        end
         new_end_date = has_recurring_end_date ? [re.recurring_end_date,end_date].min : end_date
         need_check_hide = false
         if tmp_hide_start.count != 0
@@ -315,7 +317,7 @@ class Event
                 next
               end
               if new_start != org_start
-                new_end = @end_date + w.day
+                new_end = @end_date ? @end_date + w.day : nil
                 hide = need_check_hide && tmp_hide_start2.include?(new_start.strftime("%Y-%m-%d"))
                 if hide
                   if preserve_hide
@@ -340,7 +342,9 @@ class Event
             end
           end
           @start_date += interval
-          @end_date += interval
+          if @end_date
+            @end_date += interval
+          end
         end
       else
         next