diff --git a/lib/ipaddr.rb b/lib/ipaddr.rb
index 7a5cf94830..b7877970e4 100644
--- a/lib/ipaddr.rb
+++ b/lib/ipaddr.rb
@@ -263,7 +263,8 @@ class IPAddr
   # Returns true if the ipaddr is a private address.  IPv4 addresses
   # in 10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16 as defined in RFC
   # 1918 and IPv6 Unique Local Addresses in fc00::/7 as defined in RFC
-  # 4193 are considered private.
+  # 4193 are considered private. Private IPv4 addresses in the
+  # IPv4-mapped IPv6 address range are also considered private.
   def private?
     case @family
     when Socket::AF_INET
@@ -271,7 +272,12 @@ class IPAddr
         @addr & 0xfff00000 == 0xac100000 ||  # 172.16.0.0/12
         @addr & 0xffff0000 == 0xc0a80000     # 192.168.0.0/16
     when Socket::AF_INET6
-      @addr & 0xfe00_0000_0000_0000_0000_0000_0000_0000 == 0xfc00_0000_0000_0000_0000_0000_0000_0000
+      @addr & 0xfe00_0000_0000_0000_0000_0000_0000_0000 == 0xfc00_0000_0000_0000_0000_0000_0000_0000 ||
+        (@addr & 0xffff_0000_0000 == 0xffff_0000_0000 && (
+          @addr & 0xff000000 == 0x0a000000 ||  # ::ffff:10.0.0.0/8
+          @addr & 0xfff00000 == 0xac100000 ||  # ::ffff::172.16.0.0/12
+          @addr & 0xffff0000 == 0xc0a80000     # ::ffff::192.168.0.0/16
+        ))
     else
       raise AddressFamilyError, "unsupported address family"
     end
diff --git a/test/test_ipaddr.rb b/test/test_ipaddr.rb
index c07ee2a8ee..90a7fc352a 100644
--- a/test/test_ipaddr.rb
+++ b/test/test_ipaddr.rb
@@ -426,6 +426,26 @@ class TC_Operator < Test::Unit::TestCase
     assert_equal(true,  IPAddr.new('fc84:8bf7:e905::1').private?)
     assert_equal(true,  IPAddr.new('fd84:8bf7:e905::1').private?)
     assert_equal(false, IPAddr.new('fe84:8bf7:e905::1').private?)
+
+    assert_equal(false, IPAddr.new('::ffff:0.0.0.0').private?)
+    assert_equal(false, IPAddr.new('::ffff:127.0.0.1').private?)
+
+    assert_equal(false, IPAddr.new('::ffff:8.8.8.8').private?)
+    assert_equal(true,  IPAddr.new('::ffff:10.0.0.0').private?)
+    assert_equal(true,  IPAddr.new('::ffff:10.255.255.255').private?)
+    assert_equal(false, IPAddr.new('::ffff:11.255.1.1').private?)
+
+    assert_equal(false, IPAddr.new('::ffff:172.15.255.255').private?)
+    assert_equal(true,  IPAddr.new('::ffff:172.16.0.0').private?)
+    assert_equal(true,  IPAddr.new('::ffff:172.31.255.255').private?)
+    assert_equal(false, IPAddr.new('::ffff:172.32.0.0').private?)
+
+    assert_equal(false, IPAddr.new('::ffff:190.168.0.0').private?)
+    assert_equal(true,  IPAddr.new('::ffff:192.168.0.0').private?)
+    assert_equal(true,  IPAddr.new('::ffff:192.168.255.255').private?)
+    assert_equal(false, IPAddr.new('::ffff:192.169.0.0').private?)
+
+    assert_equal(false, IPAddr.new('::ffff:169.254.0.1').private?)
   end
 
   def test_link_local?