diff --git a/lib/ipaddr.rb b/lib/ipaddr.rb
index 7fff54b9d0..6fe6c1f318 100644
--- a/lib/ipaddr.rb
+++ b/lib/ipaddr.rb
@@ -112,13 +112,12 @@ class IPAddr
   def self.ntop(addr)
     case addr.size
     when 4
-      s = addr.unpack('C4').join('.')
+      addr.unpack('C4').join('.')
     when 16
-      s = IN6FORMAT % addr.unpack('n8')
+      IN6FORMAT % addr.unpack('n8')
     else
       raise AddressFamilyError, "unsupported address family"
     end
-    return s
   end
 
   # Returns a new ipaddr built by bitwise AND.
diff --git a/test/test_ipaddr.rb b/test/test_ipaddr.rb
index 7b3a199bf3..e2243dc542 100644
--- a/test/test_ipaddr.rb
+++ b/test/test_ipaddr.rb
@@ -116,6 +116,23 @@ class TC_IPAddr < Test::Unit::TestCase
     assert_equal("192.168.2.1", IPAddr.new_ntoh(a.hton).to_s)
   end
 
+  def test_ntop
+    # IPv4
+    assert_equal("192.168.1.1", IPAddr.ntop("\xC0\xA8\x01\x01"))
+    # IPv6
+    assert_equal("0000:0000:0000:0000:0000:0000:0000:0001",
+                 IPAddr.ntop("\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01"))
+
+    # Invalid parameters
+    assert_raise(IPAddr::AddressFamilyError) {
+      IPAddr.ntop("192.168.1.1")
+    }
+
+    assert_raise(IPAddr::AddressFamilyError) {
+      IPAddr.ntop("\xC0\xA8\x01\xFF1")
+    }
+  end
+
   def test_ipv4_compat
     a = IPAddr.new("::192.168.1.2")
     assert_equal("::192.168.1.2", a.to_s)