diff --git a/app/models/time_entry.rb b/app/models/time_entry.rb
index 61b53d1c0..759f9bed0 100644
--- a/app/models/time_entry.rb
+++ b/app/models/time_entry.rb
@@ -32,7 +32,7 @@ class TimeEntry < ActiveRecord::Base
   
   validates_presence_of :user_id, :activity_id, :project_id, :hours, :spent_on
   validates_numericality_of :hours, :allow_nil => true
-  validates_length_of :comments, :maximum => 255
+  validates_length_of :comments, :maximum => 255, :allow_nil => true
 
   def after_initialize
     if new_record? && self.activity.nil?