diff --git a/test/http_signatures_test.exs b/test/http_signatures_test.exs
index b910ede..0153e0e 100644
--- a/test/http_signatures_test.exs
+++ b/test/http_signatures_test.exs
@@ -16,6 +16,8 @@ defmodule HttpSignaturesTest do
     "(request-target)" => "post /foo?param=value&pet=dog",
     "host" => "example.com",
     "date" => "Thu, 05 Jan 2014 21:31:40 GMT",
+    "(created)" => "1388957500", # the same date, in unix timestamp
+    "(expires)" => "1388967500", # 10000 seconds later
     "content-type" => "application/json",
     "digest" => "SHA-256=X48E9qOokqqrvdts8nOJRJN3OWDUoyWxBf7kbu9DBPE=",
     "content-length" => "18"
@@ -29,6 +31,16 @@ defmodule HttpSignaturesTest do
   keyId="Test",algorithm="rsa-sha256",headers="(request-target) host date",signature="HUxc9BS3P/kPhSmJo+0pQ4IsCo007vkv6bUm4Qehrx+B1Eo4Mq5/6KylET72ZpMUS80XvjlOPjKzxfeTQj4DiKbAzwJAb4HX3qX6obQTa00/qPDXlMepD2JtTw33yNnm/0xV7fQuvILN/ys+378Ysi082+4xBQFwvhNvSoVsGv4="
   """
 
+  # IO.puts HTTPSignatures.sign(@private_key, "Test", %{
+  #     "(request-target)" => "post /foo?param=value&pet=dog",
+  #     "host" => "example.com",
+  #     "(created)" => "1388957500", # the same date, in unix timestamp
+  #     "(expires)" => "1388967500", # 10000 seconds later
+  # })
+  @timestamped_signature """
+  keyId="Test",algorithm="rsa-sha256",headers="(created) (expires) (request-target) host",signature="rR4LdJSX1ZkmFmh9HUxQt0DFFPuYfvaV+mVMhEws6fMkxHO2AE0vAteYp22T7DFRYcCiXoLrqp+53aKaCX1ade2KZM7obKJ78fMZ4jETqUM9P/ziSHCIEmnNohWoGrCkpU775AXmh0A7lsfKeNLYqdYkS6G85asxn1QGWzeE4O8=",created="1388957500",expires="1388967500"
+  """
+
   @all_headers_signature """
   keyId="Test",algorithm="rsa-sha256",headers="(request-target) host date content-type digest content-length",signature="Ef7MlxLXoBovhil3AlyjtBwAL9g4TN3tibLj7uuNB3CROat/9KaeQ4hW2NiJ+pZ6HQEOx9vYZAyi+7cmIkmJszJCut5kQLAwuX+Ms/mUFvpKlSo9StS2bMXDBNjOh4Auj774GFj4gwjS+3NhFeoqyr/MuN6HsEnkvn6zdgfE2i0="
   """
@@ -55,6 +67,11 @@ defmodule HttpSignaturesTest do
     assert HTTPSignatures.validate(@headers, signature, @public_key)
   end
 
+  test "validates the timestamped case" do
+    signature = HTTPSignatures.split_signature(@timestamped_signature)
+    assert HTTPSignatures.validate(@headers, signature, @public_key)
+  end
+
   test "validates the all-headers case" do
     signature = HTTPSignatures.split_signature(@all_headers_signature)
     assert HTTPSignatures.validate(@headers, signature, @public_key)
@@ -62,7 +79,9 @@ defmodule HttpSignaturesTest do
 
   test "it contructs a signing string" do
     expected = "date: Thu, 05 Jan 2014 21:31:40 GMT\ncontent-length: 18"
-    assert expected == HTTPSignatures.build_signing_string(@headers, ["date", "content-length"], nil, nil)
+    assert expected == HTTPSignatures.build_signing_string(@headers, ["date", "content-length"], @headers["(created)"], @headers["(expires)"])
+    expected = "(created): 1388957500\n(expires): 1388967500\ncontent-length: 18"
+    assert expected == HTTPSignatures.build_signing_string(@headers, ["(created)", "(expires)", "content-length"], @headers["(created)"], @headers["(expires)"])
   end
 
   test "it parses the http signature for a conn" do