diff --git a/app/models/paper.rb b/app/models/paper.rb
index 26822fc..5d0a37b 100644
--- a/app/models/paper.rb
+++ b/app/models/paper.rb
@@ -1,3 +1,4 @@
 class Paper < ActiveRecord::Base
   validates :title, :venue, :year, presence: true
+  validates :year, numericality: { only_integer: true }
 end