diff --git a/CHANGELOG.md b/CHANGELOG.md
index 41804a5..f7d2cb8 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,5 @@
+- Recognize shorthand IPv4 addresses like [inet_aton](https://linux.die.net/man/3/inet_aton) does. [\#12](https://github.com/ruby/ipaddr/pull/12) ([Envek](https://github.com/Envek))
+
 1.3.0
 -----
 
diff --git a/lib/ipaddr.rb b/lib/ipaddr.rb
index 59427bc..605db7a 100644
--- a/lib/ipaddr.rb
+++ b/lib/ipaddr.rb
@@ -51,11 +51,17 @@ class IPAddr
   IN6FORMAT = (["%.4x"] * 8).join(':').freeze
 
   # Regexp _internally_ used for parsing IPv4 address.
+  # Accepts shorthand forms like +inet_aton+ does:
+  #   127.0.0.1 = 127.1 = 0x7f.1 = 0177.1 = 2130706433
+  #   192.168.255.255 = 192.168.65535 = 0xC0.0xA8FFFF = 3232301055
   RE_IPV4ADDRLIKE = %r{
     \A
-    \d+ \. \d+ \. \d+ \. \d+
+    (?:((?:0x?)?[\da-f]{1,3})\.)?
+    (?:((?:0x?)?[\da-f]{1,3})\.)?
+    (?:((?:0x?)?[\da-f]{1,3})\.)?
+    (?:((?:0x?)?[\da-f]{1,10}))
     \z
-  }x
+  }xi
 
   # Regexp _internally_ used for parsing IPv6 address.
   RE_IPV6ADDRLIKE_FULL = %r{
@@ -787,14 +793,19 @@ def in_addr(addr)
     when Array
       octets = addr
     else
-      RE_IPV4ADDRLIKE.match?(addr) or return nil
-      octets = addr.split('.')
-    end
-    octets.inject(0) { |i, s|
-      (n = s.to_i) < 256 or raise InvalidAddressError, "invalid address: #{addr}"
-      (s != '0') && s.start_with?('0') and raise InvalidAddressError, "zero-filled number in IPv4 address is ambiguous: #{addr}"
-      i << 8 | n
-    }
+      m = RE_IPV4ADDRLIKE.match(addr) or return nil
+      octets = m.captures
+    end
+    octets.each.with_index.inject(0) do |address, (octet, index)|
+      address = address << 8
+      next address unless octet
+
+      n = Integer(octet)
+      max_exponent = index == 3 ? 8 * (1 + octets.count(&:nil?)) : 8
+      n < 2**max_exponent or raise InvalidAddressError, "invalid address: #{addr}"
+
+      address | n
+    end
   end
 
   def in6_addr(left)
diff --git a/test/test_ipaddr.rb b/test/test_ipaddr.rb
index 6af7b73..61a8ec3 100644
--- a/test/test_ipaddr.rb
+++ b/test/test_ipaddr.rb
@@ -107,17 +107,16 @@ def test_s_new
     assert_equal("0:2:3:4:5:6:7:8", IPAddr.new("::2:3:4:5:6:7:8").to_s)
 
     assert_raise(IPAddr::InvalidAddressError) { IPAddr.new("192.168.0.256") }
-    assert_raise(IPAddr::InvalidAddressError) { IPAddr.new("192.168.0.011") }
     assert_raise(IPAddr::InvalidAddressError) { IPAddr.new("fe80::1%") }
     assert_raise(IPAddr::InvalidAddressError) { IPAddr.new("fe80::1%]") }
     assert_raise(IPAddr::InvalidAddressError) { IPAddr.new("[192.168.1.2]") }
     assert_raise(IPAddr::InvalidAddressError) { IPAddr.new("[192.168.1.2]/120") }
     assert_raise(IPAddr::InvalidAddressError) { IPAddr.new("[2001:200:300::]\nINVALID") }
     assert_raise(IPAddr::InvalidAddressError) { IPAddr.new("192.168.0.1/32\nINVALID") }
-    assert_raise(IPAddr::InvalidAddressError) { IPAddr.new("192.168.0.1/32/20") }
     assert_raise(IPAddr::InvalidAddressError) { IPAddr.new("192.168.1.2", Socket::AF_INET6) }
     assert_raise(IPAddr::InvalidAddressError) { IPAddr.new("[192.168.1.2]", Socket::AF_INET6) }
     assert_raise(IPAddr::InvalidAddressError) { IPAddr.new("[192.168.1.2]", Socket::AF_INET) }
+    assert_raise(IPAddr::InvalidPrefixError) { IPAddr.new("192.168.0.1/32/20") }
     assert_raise(IPAddr::InvalidPrefixError) { IPAddr.new("192.168.0.1/032") }
     assert_raise(IPAddr::InvalidPrefixError) { IPAddr.new("::1/0128") }
     assert_raise(IPAddr::InvalidPrefixError) { IPAddr.new("::1/255.255.255.0") }
@@ -131,6 +130,24 @@ def test_s_new
     assert_raise(IPAddr::AddressFamilyError) { IPAddr.new("[::%eth0]", Socket::AF_INET) }
   end
 
+  def test_s_new_aton_compatible
+    assert_equal("127.0.0.1",       IPAddr.new("127.1").to_s)
+    assert_equal("127.0.0.2",       IPAddr.new("0x7F.2").to_s)
+    assert_equal("127.0.0.42",      IPAddr.new("0177.42").to_s)
+    assert_equal("127.0.0.34",      IPAddr.new("0x7f.042").to_s)
+    assert_equal("127.0.0.1",       IPAddr.new("2130706433").to_s)
+    assert_equal("255.255.255.255", IPAddr.new("4294967295").to_s)
+    assert_equal("192.168.1.1",     IPAddr.new("192.168.257").to_s)
+    assert_equal("10.1.136.148",    IPAddr.new("10.100500").to_s)
+    assert_equal("192.168.0.9",     IPAddr.new("192.168.0.011").to_s)
+    assert_equal("192.168.1.100",   IPAddr.new("192.168.01.100").to_s)
+    assert_equal("192.168.255.255", IPAddr.new("0xC0.0xA8FFFF").to_s)
+
+    assert_raise(IPAddr::InvalidAddressError) { IPAddr.new("192.168.0.256") }
+    assert_raise(IPAddr::InvalidAddressError) { IPAddr.new("256.168.0.1") }
+    assert_raise(IPAddr::InvalidAddressError) { IPAddr.new("4294967296") }
+  end
+
   def test_s_new_ntoh
     addr = ''
     IPAddr.new("1234:5678:9abc:def0:1234:5678:9abc:def0").hton.each_byte { |c|
@@ -774,11 +791,6 @@ def test_raises_invalid_address_error_with_error_message
     end
     assert_equal('invalid address: 192.168.0.1000', e.message)
 
-    e = assert_raise(IPAddr::InvalidAddressError) do
-      IPAddr.new('192.168.01.100')
-    end
-    assert_equal('zero-filled number in IPv4 address is ambiguous: 192.168.01.100', e.message)
-
     e = assert_raise(IPAddr::InvalidAddressError) do
       IPAddr.new('INVALID')
     end