diff --git a/lib/tcr.rb b/lib/tcr.rb
index af42e6c..4a6b741 100644
--- a/lib/tcr.rb
+++ b/lib/tcr.rb
@@ -39,7 +39,7 @@ def save_session
 
   def use_cassette(name, options = {}, &block)
     raise ArgumentError, "`TCR.use_cassette` requires a block." unless block
-    TCR.cassette = Cassette.new(name)
+    TCR.cassette = TCR::Cassette.build(name, configuration.serialize_with)
     yield
     TCR.cassette.save
   ensure
diff --git a/lib/tcr/cassette.rb b/lib/tcr/cassette.rb
index 949bf32..270d17c 100644
--- a/lib/tcr/cassette.rb
+++ b/lib/tcr/cassette.rb
@@ -1,44 +1,16 @@
 module TCR
-  class Cassette
-    attr_reader :name
-
-    def initialize(name)
-      @name = name
-
-      if File.exists?(filename)
-        @recording = false
-        @contents = File.open(filename) { |f| f.read }
-        @sessions = JSON.parse(@contents)
-      else
-        @recording = true
-        @sessions = []
-      end
-    end
-
-    def recording?
-      @recording
-    end
-
-    def next_session
-      if recording?
-        @sessions << []
-        @sessions.last
+  module Cassette
+    def self.build(name, type)
+      case type
+      when :gzip
+        TCR::Cassette::Gzip.new(name)
       else
-        raise NoMoreSessionsError if @sessions.empty?
-        @sessions.shift
+        TCR::Cassette::JSON.new(name)
       end
     end
-
-    def save
-      if recording?
-        File.open(filename, "w") { |f| f.write(JSON.pretty_generate(@sessions)) }
-      end
-    end
-
-    protected
-
-    def filename
-      "#{TCR.configuration.cassette_library_dir}/#{name}.json"
-    end
   end
 end
+
+require "tcr/cassette/base"
+require "tcr/cassette/json"
+require "tcr/cassette/gzip"
diff --git a/lib/tcr/cassette/base.rb b/lib/tcr/cassette/base.rb
new file mode 100644
index 0000000..28646e3
--- /dev/null
+++ b/lib/tcr/cassette/base.rb
@@ -0,0 +1,41 @@
+module TCR
+  module Cassette
+    class Base
+      attr_reader :name
+
+      def initialize(name)
+        @name = name
+
+        if File.exist?(filename)
+          @recording = false
+          @sessions = deserialize
+        else
+          @recording = true
+          @sessions = []
+        end
+      end
+
+      def recording?
+        @recording
+      end
+
+      def next_session
+        if recording?
+          @sessions << []
+          @sessions.last
+        else
+          raise NoMoreSessionsError if @sessions.empty?
+          @sessions.shift
+        end
+      end
+
+      def save
+        serialize(@sessions) if recording?
+      end
+
+      def filename
+        File.join(TCR.configuration.cassette_library_dir, "#{name}.#{extension}")
+      end
+    end
+  end
+end
diff --git a/lib/tcr/cassette/gzip.rb b/lib/tcr/cassette/gzip.rb
new file mode 100644
index 0000000..22d82ee
--- /dev/null
+++ b/lib/tcr/cassette/gzip.rb
@@ -0,0 +1,25 @@
+module TCR
+  module Cassette
+    class Gzip < Base
+      def initialize(_name)
+        super
+      end
+
+      def extension
+        :gz
+      end
+
+      def serialize(data)
+        Zlib::GzipWriter.open(filename) do |gz|
+          gz.write(Marshal.dump(data))
+        end
+      end
+
+      def deserialize
+        Zlib::GzipReader.open(filename) do |gz|
+          return Marshal.load(gz.read)
+        end
+      end
+    end
+  end
+end
diff --git a/lib/tcr/cassette/json.rb b/lib/tcr/cassette/json.rb
new file mode 100644
index 0000000..b88ad5e
--- /dev/null
+++ b/lib/tcr/cassette/json.rb
@@ -0,0 +1,21 @@
+module TCR
+  module Cassette
+    class JSON < Base
+      def initialize(_name)
+        super
+      end
+
+      def extension
+        :json
+      end
+
+      def serialize(data)
+        File.binwrite(filename, ::JSON.pretty_generate(data))
+      end
+
+      def deserialize
+        ::JSON.parse(File.binread(filename))
+      end
+    end
+  end
+end
diff --git a/lib/tcr/configuration.rb b/lib/tcr/configuration.rb
index b60aada..17efc06 100644
--- a/lib/tcr/configuration.rb
+++ b/lib/tcr/configuration.rb
@@ -1,6 +1,6 @@
 module TCR
   class Configuration
-    attr_accessor :cassette_library_dir, :hook_tcp_ports, :block_for_reads
+    attr_accessor :cassette_library_dir, :hook_tcp_ports, :block_for_reads, :serialize_with
 
     def initialize
       reset_defaults!
@@ -10,6 +10,7 @@ def reset_defaults!
       @cassette_library_dir = "fixtures/tcr_cassettes"
       @hook_tcp_ports = []
       @block_for_reads = false
+      @serialize_with = :json
     end
   end
 end
diff --git a/lib/tcr/recordable_tcp_socket.rb b/lib/tcr/recordable_tcp_socket.rb
index 0de0793..9e86c87 100644
--- a/lib/tcr/recordable_tcp_socket.rb
+++ b/lib/tcr/recordable_tcp_socket.rb
@@ -5,6 +5,16 @@
 
 module TCR
   class RecordableTCPSocket
+    module MockedIO
+      def self.wait_readable(_timeout)
+        true
+      end
+
+      def self.wait_writable(_timeout)
+        true
+      end
+    end
+
     attr_reader :live, :socket
     attr_accessor :recording
 
@@ -46,6 +56,8 @@ def write(str)
     def to_io
       if live
         @socket.to_io
+      else
+        MockedIO
       end
     end
 
diff --git a/spec/fixtures/google_http.gz b/spec/fixtures/google_http.gz
new file mode 100644
index 0000000..b92d15b
Binary files /dev/null and b/spec/fixtures/google_http.gz differ
diff --git a/spec/tcr_spec.rb b/spec/tcr_spec.rb
index d1f1996..343fc59 100644
--- a/spec/tcr_spec.rb
+++ b/spec/tcr_spec.rb
@@ -31,7 +31,11 @@
      it "defaults to erroring on read/write mismatch access" do
        TCR.configuration.block_for_reads.should be_falsey
      end
-   end
+
+     it "has a default cassette type" do
+       TCR.configuration.serialize_with.should == :json
+     end
+  end
 
    describe ".configure" do
      it "configures cassette location" do
@@ -51,6 +55,12 @@
          TCR.configure { |c| c.block_for_reads = true }
        }.to change{ TCR.configuration.block_for_reads }.from(false).to(true)
      end
+
+     it "configures cassette type" do
+       expect {
+         TCR.configure { |c| c.serialize_with = :gzip }
+       }.to change{ TCR.configuration.serialize_with }.from(:json).to(:gzip)
+     end
    end
 
    it "raises an error if you connect to a hooked port without using a cassette" do
@@ -225,6 +235,20 @@
       }.not_to raise_error
     end
 
+    it "supports gzip cassettes" do
+      TCR.configure { |c|
+        c.hook_tcp_ports = [80]
+        c.serialize_with = :gzip
+      }
+
+      expect {
+        TCR.use_cassette("spec/fixtures/google_http") do
+          body = Net::HTTP.get(URI('http://google.com/'))
+          expect(body).to_not be_empty
+        end
+      }.not_to raise_error
+    end
+
     it "can stub the full session of a real server accepting a real email over SMTPS with STARTTLS" do
       TCR.configure { |c|
         c.hook_tcp_ports = [587]