diff --git a/lib/ipaddr.rb b/lib/ipaddr.rb
index 525466b..0913837 100644
--- a/lib/ipaddr.rb
+++ b/lib/ipaddr.rb
@@ -167,7 +167,7 @@ def ==(other)
   rescue
     false
   else
-    @family == other.family && @addr == other.to_i
+    @family == other.family && @addr == other.to_i && @mask_addr == other.instance_variable_get(:@mask_addr)
   end
 
   # Returns a new ipaddr built by masking IP address with the given
diff --git a/test/test_ipaddr.rb b/test/test_ipaddr.rb
index 7ecd37e..9b59f66 100644
--- a/test/test_ipaddr.rb
+++ b/test/test_ipaddr.rb
@@ -440,12 +440,16 @@ def test_minus
   end
 
   def test_equal
-    assert_equal(true, @a == IPAddr.new("3FFE:505:2::"))
-    assert_equal(true, @a == IPAddr.new("3ffe:0505:0002::"))
-    assert_equal(true, @a == IPAddr.new("3ffe:0505:0002:0:0:0:0:0"))
-    assert_equal(false, @a == IPAddr.new("3ffe:505:3::"))
+    assert_equal(true, @a == IPAddr.new("3FFE:0505:2::/48"))
+    assert_equal(true, @a == IPAddr.new("3ffe:0505:0002::/48"))
+    assert_equal(true, @a == IPAddr.new("3ffe:0505:0002:0:0:0:0:0/48"))
+    assert_equal(false, @a == IPAddr.new("3FFE:505:2::"))
+    assert_equal(false, @a == IPAddr.new("3ffe:0505:0002::"))
+    assert_equal(false, @a == IPAddr.new("3ffe:0505:0002:0:0:0:0:0"))
+    assert_equal(false, @a == IPAddr.new("3ffe:0505:2::1/128"))
+    assert_equal(false, @a == IPAddr.new("3ffe:0505:0002:0:0:0:0:1/128"))
     assert_equal(true, @a != IPAddr.new("3ffe:505:3::"))
-    assert_equal(false, @a != IPAddr.new("3ffe:505:2::"))
+    assert_equal(true, @a != IPAddr.new("3ffe:505:2::"))
     assert_equal(false, @a == @inconvertible_range)
     assert_equal(false, @a == @inconvertible_string)
   end