diff --git a/lib/mini_defender/rules/expiry_date.rb b/lib/mini_defender/rules/expiry_date.rb
index 96d745d..e9aca8a 100644
--- a/lib/mini_defender/rules/expiry_date.rb
+++ b/lib/mini_defender/rules/expiry_date.rb
@@ -17,7 +17,7 @@ def passes?(attribute, value, validator)
 
     @month = matches[1].to_i
     @year = matches[2].to_i
-    @year += 2000 if year < 100
+    @year += 2000 if @year < 100
 
     @month >= 1 && @month <= 12 && @year >= 1900
   end
diff --git a/test/rules/expiry_date_test.rb b/test/rules/expiry_date_test.rb
index af569af..385dfc4 100644
--- a/test/rules/expiry_date_test.rb
+++ b/test/rules/expiry_date_test.rb
@@ -3,5 +3,34 @@
 require 'test_helper'
 
 class ExpiryDateTest < Minitest::Test
+    def setup
+        @rule = MiniDefender::Rules::ExpiryDate.new
+    end
 
+    def test_signature
+        assert_equal 'expiry_date', MiniDefender::Rules::ExpiryDate.signature
+    end
+
+    def test_passes_with_valid_dates
+        assert_equal @rule.passes?('expiry', '12/25', nil), true
+        assert_equal @rule.passes?('expiry', '01 / 2030', nil), true
+        assert_equal @rule.passes?('expiry', ' 06/99 ', nil) , true
+    end
+
+    def test_passes_with_invalid_dates
+        assert_equal @rule.passes?('expiry', '13/25', nil), false
+        assert_equal @rule.passes?('expiry', '00/2025', nil), false
+        assert_equal @rule.passes?('expiry', '11-2025', nil), false
+        assert_equal @rule.passes?('expiry', 'abcd', nil), false
+        assert_equal @rule.passes?('expiry', '06/1899', nil), false
+    end
+
+    def test_message
+        assert_equal 'Invalid expiry date.', @rule.message('expiry', '13/25', nil)
+    end
+
+    def test_coerce
+        @rule.passes?('expiry', '06/25', nil)
+        assert_equal '6/2025', @rule.coerce(nil)
+    end
 end