diff --git a/lib/openflow/multipart/aggregate/reply.ex b/lib/openflow/multipart/aggregate/reply.ex
index 7b710c2..dfecbf0 100644
--- a/lib/openflow/multipart/aggregate/reply.ex
+++ b/lib/openflow/multipart/aggregate/reply.ex
@@ -13,9 +13,59 @@ defmodule Openflow.Multipart.Aggregate.Reply do
 
   alias __MODULE__
 
-  def ofp_type, do: 18
+  @type t :: %Reply{
+          version: 4,
+          xid: 0..0xFFFFFFFF,
+          datapath_id: String.t() | nil,
+          aux_id: 0..0xFF,
+          flags: [],
+          packet_count: 0..0xFFFFFFFFFFFFFFFF,
+          byte_count: 0..0xFFFFFFFFFFFFFFFF,
+          flow_count: 0..0xFFFFFFFF
+        }
 
-  def read(<<packet_count::64, byte_count::64, flow_count::32, _::size(4)-unit(8)>>) do
-    %Reply{packet_count: packet_count, byte_count: byte_count, flow_count: flow_count}
+  @spec ofp_type() :: 19
+  def ofp_type, do: 19
+
+  @spec new(
+          xid: 0..0xFFFFFFFF,
+          flags: [],
+          packet_count: 0..0xFFFFFFFFFFFFFFFF,
+          byte_count: 0..0xFFFFFFFFFFFFFFFF,
+          flow_count: 0..0xFFFFFFFF
+        ) :: t()
+  def new(options \\ []) do
+    %Reply{
+      xid: options[:xid] || 0,
+      flags: options[:flags] || [],
+      packet_count: options[:packet_count] || 0,
+      byte_count: options[:byte_count] || 0,
+      flow_count: options[:flow_count] || 0
+    }
+  end
+
+  @spec to_binary(t()) :: <<_::192>>
+  def to_binary(aggregate) do
+    <<
+      Openflow.Multipart.Reply.header(aggregate)::bytes,
+      aggregate.packet_count::64,
+      aggregate.byte_count::64,
+      aggregate.flow_count::32,
+      0::size(4)-unit(8)
+    >>
+  end
+
+  @spec read(<<_::192>>) :: t()
+  def read(<<
+        packet_count::64,
+        byte_count::64,
+        flow_count::32,
+        _::size(4)-unit(8)
+      >>) do
+    %Reply{
+      packet_count: packet_count,
+      byte_count: byte_count,
+      flow_count: flow_count
+    }
   end
 end
diff --git a/test/lib/openflow/ofp_aggregate_test.exs b/test/lib/openflow/ofp_aggregate_test.exs
new file mode 100644
index 0000000..a6c7a08
--- /dev/null
+++ b/test/lib/openflow/ofp_aggregate_test.exs
@@ -0,0 +1,40 @@
+defmodule OfpAggregateTest do
+  use ExUnit.Case
+
+  describe "Openflow.Multipart.Aggregate.Request" do
+    test "with default values" do
+      aggregate =
+        %Openflow.Multipart.Aggregate.Request{}
+        |> Map.to_list()
+        |> Openflow.Multipart.Aggregate.Request.new()
+        |> Openflow.to_binary()
+        |> Openflow.read()
+        |> Kernel.elem(1)
+
+      assert aggregate.xid == 0
+      assert aggregate.table_id == :all
+      assert aggregate.out_port == :any
+      assert aggregate.out_group == :any
+      assert aggregate.cookie == 0
+      assert aggregate.cookie_mask == 0
+      assert aggregate.match == []
+    end
+  end
+
+  describe "Openflow.Multipart.Aggregate.Reply" do
+    test "with default values" do
+      aggregate =
+        %Openflow.Multipart.Aggregate.Reply{}
+        |> Map.to_list()
+        |> Openflow.Multipart.Aggregate.Reply.new()
+        |> Openflow.to_binary()
+        |> Openflow.read()
+        |> Kernel.elem(1)
+
+      assert aggregate.xid == 0
+      assert aggregate.packet_count == 0
+      assert aggregate.byte_count == 0
+      assert aggregate.flow_count == 0
+    end
+  end
+end