diff --git a/.commit/config.yml b/.commit/config.yml
index cafdc74..b870728 100644
--- a/.commit/config.yml
+++ b/.commit/config.yml
@@ -53,4 +53,6 @@ ruby:
         spec.files = Dir["CHANGELOG.md", "README.md", "LICENSE", "lib/**/*"]
         spec.require_path = "lib"
 
-        spec.extensions = %w[ext/llhttp/extconf.rb]
+        spec.extensions = %w[ext/Rakefile]
+
+        spec.add_dependency "ffi-compiler", "~> 1.0"
diff --git a/LICENSE b/LICENSE
index c7ad8c2..1ee96d4 100644
--- a/LICENSE
+++ b/LICENSE
@@ -1,6 +1,6 @@
 This software is licensed under the MIT License.
 
-Copyright 2020 Metabahn.
+Copyright 2020-2021 Metabahn.
 
 Permission is hereby granted, free of charge, to any person obtaining a
 copy of this software and associated documentation files (the
diff --git a/Rakefile b/Rakefile
index 264a5cb..2aa9a65 100644
--- a/Rakefile
+++ b/Rakefile
@@ -1,11 +1,9 @@
 # frozen_string_literal: true
 
 require "fileutils"
-require "rake/extensiontask"
 
-Rake::ExtensionTask.new "llhttp_ext" do |ext|
-  ext.ext_dir = "ext/llhttp"
-  ext.lib_dir = "lib/llhttp"
+task :compile do
+  system "cd ext && bundle exec rake"
 end
 
 task test: :compile do
diff --git a/benchmarks/ffi/Gemfile b/benchmarks/ffi/Gemfile
new file mode 100644
index 0000000..bf76ed8
--- /dev/null
+++ b/benchmarks/ffi/Gemfile
@@ -0,0 +1,8 @@
+# frozen_string_literal: true
+
+source "https://rubygems.org"
+
+gem "llhttp", path: "../.."
+
+gem "benchmark-ips"
+gem "ruby-prof"
diff --git a/benchmarks/ffi/run.rb b/benchmarks/ffi/run.rb
new file mode 100644
index 0000000..9bc3572
--- /dev/null
+++ b/benchmarks/ffi/run.rb
@@ -0,0 +1,20 @@
+# frozen_string_literal: true
+
+require_relative "../shared"
+
+benchmark
+
+# require "ruby-prof"
+
+# delegate = LLHttp::Delegate.new
+# instance = LLHttp::Parser.new(delegate, type: :request)
+
+# result = RubyProf.profile {
+#   1_000_000.times do
+#     parse(instance)
+#     instance.finish
+#   end
+# }
+
+# printer = RubyProf::GraphPrinter.new(result)
+# printer.print(STDOUT, {})
diff --git a/benchmarks/mri/Gemfile b/benchmarks/mri/Gemfile
new file mode 100644
index 0000000..7b56a3f
--- /dev/null
+++ b/benchmarks/mri/Gemfile
@@ -0,0 +1,6 @@
+# frozen_string_literal: true
+
+source "https://rubygems.org"
+
+gem "benchmark-ips"
+gem "llhttp"
diff --git a/benchmarks/mri/run.rb b/benchmarks/mri/run.rb
new file mode 100644
index 0000000..1b0314c
--- /dev/null
+++ b/benchmarks/mri/run.rb
@@ -0,0 +1,5 @@
+# frozen_string_literal: true
+
+require_relative "../shared"
+
+benchmark
diff --git a/benchmarks/shared.rb b/benchmarks/shared.rb
new file mode 100644
index 0000000..1b42d0f
--- /dev/null
+++ b/benchmarks/shared.rb
@@ -0,0 +1,26 @@
+# frozen_string_literal: true
+
+require "benchmark/ips"
+require "llhttp"
+
+def parse(instance)
+  instance << "GET / HTTP/1.1\r\n"
+  instance << "content-length: 18\r\n"
+  instance << "\r\n"
+  instance << "body1\n"
+  instance << "body2\n"
+  instance << "body3\n"
+  instance << "\r\n"
+end
+
+def benchmark
+  delegate = LLHttp::Delegate.new
+  instance = LLHttp::Parser.new(delegate, type: :request)
+
+  Benchmark.ips do |x|
+    x.report do
+      parse(instance)
+      instance.finish
+    end
+  end
+end
diff --git a/ext/Rakefile b/ext/Rakefile
new file mode 100644
index 0000000..e169dcd
--- /dev/null
+++ b/ext/Rakefile
@@ -0,0 +1,5 @@
+# frozen_string_literal: true
+
+require "ffi-compiler/compile_task"
+
+FFI::Compiler::CompileTask.new("llhttp-ext")
diff --git a/ext/llhttp/extconf.rb b/ext/llhttp/extconf.rb
deleted file mode 100644
index 65cfc3f..0000000
--- a/ext/llhttp/extconf.rb
+++ /dev/null
@@ -1,7 +0,0 @@
-# frozen_string_literal: true
-
-require "mkmf"
-
-dir_config "llhttp_ext"
-
-create_makefile "llhttp_ext"
diff --git a/ext/llhttp/llhttp_ext.c b/ext/llhttp/llhttp_ext.c
index c31ea54..15ab37e 100644
--- a/ext/llhttp/llhttp_ext.c
+++ b/ext/llhttp/llhttp_ext.c
@@ -21,223 +21,147 @@
 // OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
 // USE OR OTHER DEALINGS IN THE SOFTWARE.
 
-#include <ruby/ruby.h>
-
+#include <stdlib.h>
+#include <string.h>
 #include "llhttp.h"
 
-static VALUE mLLHttp, cParser, eError;
+typedef struct rb_llhttp_callbacks_s rb_llhttp_callbacks_t;
 
-static void rb_llhttp_free(llhttp_t *parser) {
-  if (parser) {
-    free(parser->settings);
-    free(parser);
-  }
-}
+typedef int (*rb_llhttp_data_cb)(const char *data, size_t length);
+typedef int (*rb_llhttp_cb)();
 
-VALUE rb_llhttp_allocate(VALUE klass) {
-  llhttp_t *parser = (llhttp_t *)malloc(sizeof(llhttp_t));
-  llhttp_settings_t *settings = (llhttp_settings_t *)malloc(sizeof(llhttp_settings_t));
+struct rb_llhttp_callbacks_s {
+  /* Possible return values 0, -1, `HPE_PAUSED` */
+  rb_llhttp_cb      on_message_begin;
 
-  llhttp_settings_init(settings);
-  llhttp_init(parser, HTTP_BOTH, settings);
+  rb_llhttp_data_cb on_url;
+  rb_llhttp_data_cb on_status;
+  rb_llhttp_data_cb on_header_field;
+  rb_llhttp_data_cb on_header_value;
 
-  return Data_Wrap_Struct(klass, 0, rb_llhttp_free, parser);
-}
-
-void rb_llhttp_callback_call(VALUE delegate, const char *name) {
-  rb_funcall(delegate, rb_intern(name), 0);
-}
+  /* Possible return values:
+   * 0  - Proceed normally
+   * 1  - Assume that request/response has no body, and proceed to parsing the
+   *      next message
+   * 2  - Assume absence of body (as above) and make `llhttp_execute()` return
+   *      `HPE_PAUSED_UPGRADE`
+   * -1 - Error
+   * `HPE_PAUSED`
+   */
+  rb_llhttp_cb      on_headers_complete;
 
-void rb_llhttp_data_callback_call(VALUE delegate, const char *name, char *data, size_t length) {
-  rb_funcall(delegate, rb_intern(name), 1, rb_str_new(data, length));
-}
+  rb_llhttp_data_cb on_body;
 
-int rb_llhttp_on_message_begin(llhttp_t *parser) {
-  VALUE delegate = (VALUE)parser->data;
+  /* Possible return values 0, -1, `HPE_PAUSED` */
+  rb_llhttp_cb      on_message_complete;
 
-  rb_llhttp_callback_call(delegate, "on_message_begin");
+  /* When on_chunk_header is called, the current chunk length is stored
+   * in parser->content_length.
+   * Possible return values 0, -1, `HPE_PAUSED`
+   */
+  rb_llhttp_cb      on_chunk_header;
+  rb_llhttp_cb      on_chunk_complete;
+};
 
+int rb_llhttp_on_message_begin(llhttp_t *parser) {
+  rb_llhttp_callbacks_t* callbacks = parser->data;
+  callbacks->on_message_begin();
   return 0;
 }
 
 int rb_llhttp_on_url(llhttp_t *parser, char *data, size_t length) {
-  VALUE delegate = (VALUE)parser->data;
-
-  rb_llhttp_data_callback_call(delegate, "on_url", data, length);
-
+  rb_llhttp_callbacks_t* callbacks = parser->data;
+  callbacks->on_url(data, length);
   return 0;
 }
 
 int rb_llhttp_on_status(llhttp_t *parser, char *data, size_t length) {
-  VALUE delegate = (VALUE)parser->data;
-
-  rb_llhttp_data_callback_call(delegate, "on_status", data, length);
-
+  rb_llhttp_callbacks_t* callbacks = parser->data;
+  callbacks->on_status(data, length);
   return 0;
 }
 
 int rb_llhttp_on_header_field(llhttp_t *parser, char *data, size_t length) {
-  VALUE delegate = (VALUE)parser->data;
-
-  rb_llhttp_data_callback_call(delegate, "on_header_field", data, length);
-
+  rb_llhttp_callbacks_t* callbacks = parser->data;
+  callbacks->on_header_field(data, length);
   return 0;
 }
 
 int rb_llhttp_on_header_value(llhttp_t *parser, char *data, size_t length) {
-  VALUE delegate = (VALUE)parser->data;
-
-  rb_llhttp_data_callback_call(delegate, "on_header_value", data, length);
-
+  rb_llhttp_callbacks_t* callbacks = parser->data;
+  callbacks->on_header_value(data, length);
   return 0;
 }
 
 int rb_llhttp_on_headers_complete(llhttp_t *parser) {
-  VALUE delegate = (VALUE)parser->data;
-
-  rb_llhttp_callback_call(delegate, "on_headers_complete");
-
+  rb_llhttp_callbacks_t* callbacks = parser->data;
+  callbacks->on_headers_complete();
   return 0;
 }
 
 int rb_llhttp_on_body(llhttp_t *parser, char *data, size_t length) {
-  VALUE delegate = (VALUE)parser->data;
-
-  rb_llhttp_data_callback_call(delegate, "on_body", data, length);
-
+  rb_llhttp_callbacks_t* callbacks = parser->data;
+  callbacks->on_body(data, length);
   return 0;
 }
 
 int rb_llhttp_on_message_complete(llhttp_t *parser) {
-  VALUE delegate = (VALUE)parser->data;
-
-  rb_llhttp_callback_call(delegate, "on_message_complete");
-
+  rb_llhttp_callbacks_t* callbacks = parser->data;
+  callbacks->on_message_complete();
   return 0;
 }
 
 int rb_llhttp_on_chunk_header(llhttp_t *parser) {
-  VALUE delegate = (VALUE)parser->data;
-
-  rb_llhttp_callback_call(delegate, "on_chunk_header");
-
+  rb_llhttp_callbacks_t* callbacks = parser->data;
+  callbacks->on_chunk_header();
   return 0;
 }
 
 int rb_llhttp_on_chunk_complete(llhttp_t *parser) {
-  VALUE delegate = (VALUE)parser->data;
-
-  rb_llhttp_callback_call(delegate, "on_chunk_complete");
-
+  rb_llhttp_callbacks_t* callbacks = parser->data;
+  callbacks->on_chunk_complete();
   return 0;
 }
 
-VALUE rb_llhttp_parse(VALUE self, VALUE data) {
-  llhttp_t *parser;
-
-  Data_Get_Struct(self, llhttp_t, parser);
-
-  enum llhttp_errno err = llhttp_execute(parser, RSTRING_PTR(data), RSTRING_LEN(data));
-
-  if (err != HPE_OK) {
-    rb_raise(eError, "Error Parsing data: %s %s", llhttp_errno_name(err), parser->reason);
-  }
-
-  return Qtrue;
-}
-
-VALUE rb_llhttp_finish(VALUE self) {
-  llhttp_t *parser;
-
-  Data_Get_Struct(self, llhttp_t, parser);
+// TODO: Don't forget the finalizer to dealloc things.
 
-  enum llhttp_errno err = llhttp_finish(parser);
-
-  if (err != HPE_OK) {
-    rb_raise(eError, "Error Parsing data: %s %s", llhttp_errno_name(err), parser->reason);
-  }
-
-  return Qtrue;
-}
-
-VALUE rb_llhttp_content_length(VALUE self) {
-  llhttp_t *parser;
-
-  Data_Get_Struct(self, llhttp_t, parser);
-
-  return UINT2NUM(parser->content_length);
-}
-
-VALUE rb_llhttp_method(VALUE self) {
-  llhttp_t *parser;
-
-  Data_Get_Struct(self, llhttp_t, parser);
-
-  return rb_str_new_cstr(llhttp_method_name(parser->method));
-}
-
-VALUE rb_llhttp_status_code(VALUE self) {
-  llhttp_t *parser;
-
-  Data_Get_Struct(self, llhttp_t, parser);
-
-  return UINT2NUM(parser->status_code);
-}
-
-VALUE rb_llhttp_keep_alive(VALUE self) {
-  llhttp_t *parser;
-
-  Data_Get_Struct(self, llhttp_t, parser);
-
-  int ret = llhttp_should_keep_alive(parser);
-
-  return ret == 1 ? Qtrue : Qfalse;
-}
-
-static VALUE rb_llhttp_init(VALUE self, VALUE type) {
-  llhttp_t *parser;
-
-  Data_Get_Struct(self, llhttp_t, parser);
+llhttp_t* rb_llhttp_init(int type, rb_llhttp_callbacks_t* callbacks) {
+  llhttp_t *parser = (llhttp_t *)malloc(sizeof(llhttp_t));
+  llhttp_settings_t *settings = (llhttp_settings_t *)malloc(sizeof(llhttp_settings_t));
 
-  llhttp_settings_t *settings = parser->settings;
+  llhttp_settings_init(settings);
 
   settings->on_message_begin = (llhttp_cb)rb_llhttp_on_message_begin;
+
   settings->on_url = (llhttp_data_cb)rb_llhttp_on_url;
   settings->on_status = (llhttp_data_cb)rb_llhttp_on_status;
   settings->on_header_field = (llhttp_data_cb)rb_llhttp_on_header_field;
   settings->on_header_value = (llhttp_data_cb)rb_llhttp_on_header_value;
+
   settings->on_headers_complete = (llhttp_cb)rb_llhttp_on_headers_complete;
+
   settings->on_body = (llhttp_data_cb)rb_llhttp_on_body;
+
   settings->on_message_complete = (llhttp_cb)rb_llhttp_on_message_complete;
+
   settings->on_chunk_header = (llhttp_cb)rb_llhttp_on_chunk_header;
   settings->on_chunk_complete = (llhttp_cb)rb_llhttp_on_chunk_complete;
 
-  llhttp_init(parser, FIX2INT(type), settings);
+  llhttp_init(parser, type, settings);
 
-  // Store a pointer to the delegate for lookup in callbacks.
-  //
-  VALUE delegate = rb_iv_get(self, "@delegate");
-  parser->data = (void*)delegate;
+  parser->data = callbacks;
 
-  return Qtrue;
+  return parser;
 }
 
-void Init_llhttp_ext(void) {
-  mLLHttp = rb_const_get(rb_cObject, rb_intern("LLHttp"));
-  cParser = rb_const_get(mLLHttp, rb_intern("Parser"));
-  eError = rb_const_get(mLLHttp, rb_intern("Error"));
-
-  rb_define_alloc_func(cParser, rb_llhttp_allocate);
-
-  rb_define_method(cParser, "<<", rb_llhttp_parse, 1);
-  rb_define_method(cParser, "parse", rb_llhttp_parse, 1);
-  rb_define_method(cParser, "finish", rb_llhttp_finish, 0);
-
-  rb_define_method(cParser, "content_length", rb_llhttp_content_length, 0);
-  rb_define_method(cParser, "method", rb_llhttp_method, 0);
-  rb_define_method(cParser, "status_code", rb_llhttp_status_code, 0);
+uint64_t rb_llhttp_content_length(llhttp_t* parser) {
+  return parser->content_length;
+}
 
-  rb_define_method(cParser, "keep_alive?", rb_llhttp_keep_alive, 0);
+const char* rb_llhttp_method_name(llhttp_t* parser) {
+  return llhttp_method_name(parser->method);
+}
 
-  rb_define_private_method(cParser, "llhttp_init", rb_llhttp_init, 1);
+uint16_t rb_llhttp_status_code(llhttp_t* parser) {
+  return parser->status_code;
 }
diff --git a/lib/llhttp.rb b/lib/llhttp.rb
index 7dd7933..58b5267 100644
--- a/lib/llhttp.rb
+++ b/lib/llhttp.rb
@@ -1,8 +1,43 @@
 # frozen_string_literal: true
 
+require "ffi"
+require "ffi-compiler/loader"
+
 module LLHttp
   require_relative "llhttp/delegate"
   require_relative "llhttp/error"
   require_relative "llhttp/parser"
   require_relative "llhttp/version"
+
+  extend FFI::Library
+  ffi_lib(FFI::Compiler::Loader.find("llhttp-ext"))
+
+  # TODO: These should return int, which should be returned to llhttp. Document possible return values.
+  #
+  callback :llhttp_data_cb, [:pointer, :size_t], :void
+  callback :llhttp_cb, [], :void
+
+  class Callbacks < FFI::Struct
+    layout :on_message_begin, :llhttp_cb,
+      :on_url, :llhttp_data_cb,
+      :on_status, :llhttp_data_cb,
+      :on_header_field, :llhttp_data_cb,
+      :on_header_value, :llhttp_data_cb,
+      :on_headers_complete, :llhttp_cb,
+      :on_body, :llhttp_data_cb,
+      :on_message_complete, :llhttp_cb,
+      :on_chunk_header, :llhttp_cb,
+      :on_chunk_complete, :llhttp_cb
+  end
+
+  attach_function :rb_llhttp_init, [:int, Callbacks.by_ref], :pointer
+  attach_function :rb_llhttp_content_length, [:pointer], :uint64
+  attach_function :rb_llhttp_method_name, [:pointer], :string
+  attach_function :rb_llhttp_status_code, [:pointer], :uint16
+
+  attach_function :llhttp_execute, [:pointer, :pointer, :size_t], :int
+  # attach_function :llhttp_errno_name, [:int], :pointer
+  # attach_function :llhttp_get_error_reason, [Instance.by_ref], :pointer
+  attach_function :llhttp_should_keep_alive, [:pointer], :int
+  attach_function :llhttp_finish, [:pointer], :int
 end
diff --git a/lib/llhttp/parser.rb b/lib/llhttp/parser.rb
index 6f02644..ab43381 100644
--- a/lib/llhttp/parser.rb
+++ b/lib/llhttp/parser.rb
@@ -20,7 +20,7 @@ module LLHttp
   # Introspection
   #
   #   * `LLHttp::Parser#content_length` returns the content length of the current request.
-  #   * `LLHttp::Parser#method` returns the method of the current response.
+  #   * `LLHttp::Parser#method_name` returns the method of the current response.
   #   * `LLHttp::Parser#status_code` returns the status code of the current response.
   #   * `LLHttp::Parser#keep_alive?` returns `true` if there might be more messages.
   #
@@ -31,16 +31,78 @@ module LLHttp
   class Parser
     LLHTTP_TYPES = {both: 0, request: 1, response: 2}.freeze
 
-    # [public] The parser type; one of: `both`, `request`, or `response`.
+    # [public] The parser type; one of: `:both`, `:request`, or `:response`.
     #
     attr_reader :type
 
     def initialize(delegate, type: :both)
       @type, @delegate = type.to_sym, delegate
 
-      llhttp_init(LLHTTP_TYPES.fetch(@type))
+      @callbacks = Callbacks.new
+      @callbacks[:on_message_begin] = delegate.method(:on_message_begin).to_proc
+      @callbacks[:on_url] = method(:on_url).to_proc
+      @callbacks[:on_status] = method(:on_status).to_proc
+      @callbacks[:on_header_field] = method(:on_header_field).to_proc
+      @callbacks[:on_header_value] = method(:on_header_value).to_proc
+      @callbacks[:on_headers_complete] = delegate.method(:on_headers_complete).to_proc
+      @callbacks[:on_body] = method(:on_body).to_proc
+      @callbacks[:on_message_complete] = delegate.method(:on_message_complete).to_proc
+      @callbacks[:on_chunk_header] = delegate.method(:on_chunk_header).to_proc
+      @callbacks[:on_chunk_complete] = delegate.method(:on_chunk_complete).to_proc
+
+      @pointer = LLHttp.rb_llhttp_init(LLHTTP_TYPES.fetch(@type), @callbacks)
+    end
+
+    def parse(data)
+      errno = LLHttp.llhttp_execute(@pointer, data, data.length)
+      raise build_error(errno) if errno > 0
+    end
+    alias_method :<<, :parse
+
+    def content_length
+      LLHttp.rb_llhttp_content_length(@pointer)
+    end
+
+    def method_name
+      LLHttp.rb_llhttp_method_name(@pointer)
+    end
+
+    def status_code
+      LLHttp.rb_llhttp_status_code(@pointer)
+    end
+
+    def keep_alive?
+      LLHttp.llhttp_should_keep_alive(@pointer) == 1
+    end
+
+    def finish
+      LLHttp.llhttp_finish(@pointer)
+    end
+
+    private def on_url(buffer, length)
+      @delegate.on_url(buffer.get_bytes(0, length))
+    end
+
+    private def on_status(buffer, length)
+      @delegate.on_status(buffer.get_bytes(0, length))
+    end
+
+    private def on_header_field(buffer, length)
+      @delegate.on_header_field(buffer.get_bytes(0, length))
+    end
+
+    private def on_header_value(buffer, length)
+      @delegate.on_header_value(buffer.get_bytes(0, length))
+    end
+
+    private def on_body(buffer, length)
+      @delegate.on_body(buffer.get_bytes(0, length))
+    end
+
+    private def build_error(errno)
+      # Error.new("Error Parsing data: #{LLHttp.llhttp_errno_name(errno).read_string} #{LLHttp.llhttp_get_error_reason(self).read_string}")
+
+      Error.new("TODO")
     end
   end
 end
-
-require_relative "llhttp_ext"
diff --git a/llhttp.gemspec b/llhttp.gemspec
index fdc2952..9e01134 100644
--- a/llhttp.gemspec
+++ b/llhttp.gemspec
@@ -19,5 +19,7 @@ Gem::Specification.new do |spec|
   spec.files = Dir["CHANGELOG.md", "README.md", "LICENSE", "lib/**/*"]
   spec.require_path = "lib"
 
-  spec.extensions = %w[ext/llhttp/extconf.rb]
+  spec.extensions = %w[ext/Rakefile]
+
+  spec.add_dependency "ffi-compiler", "~> 1.0"
 end
diff --git a/spec/integration/parser/request_parsing/errors_spec.rb b/spec/integration/parser/request_parsing/errors_spec.rb
index 5c3f7ee..4abca0e 100644
--- a/spec/integration/parser/request_parsing/errors_spec.rb
+++ b/spec/integration/parser/request_parsing/errors_spec.rb
@@ -1,5 +1,7 @@
 # frozen_string_literal: true
 
+require "llhttp"
+
 RSpec.describe "errors when parsing requests" do
   let(:instance) {
     LLHttp::Parser.new(LLHttp::Delegate.new, type: :request)
diff --git a/spec/integration/parser/request_parsing/introspection_spec.rb b/spec/integration/parser/request_parsing/introspection_spec.rb
index 5ac90e3..29cd4dc 100644
--- a/spec/integration/parser/request_parsing/introspection_spec.rb
+++ b/spec/integration/parser/request_parsing/introspection_spec.rb
@@ -51,11 +51,11 @@ def on_headers_complete
     end
   end
 
-  describe "method" do
+  describe "method_name" do
     let(:extension) {
       proc {
         def on_headers_complete
-          @context.instance_variable_set(:@method, @context.instance.method)
+          @context.instance_variable_set(:@method_name, @context.instance.method_name)
         end
       }
     }
@@ -63,7 +63,23 @@ def on_headers_complete
     it "returns the content" do
       parse
 
-      expect(@method).to eq("GET")
+      expect(@method_name).to eq("GET")
+    end
+  end
+
+  describe "keep_alive" do
+    let(:extension) {
+      proc {
+        def on_headers_complete
+          @context.instance_variable_set(:@keep_alive, @context.instance.keep_alive?)
+        end
+      }
+    }
+
+    it "returns the keep alive state" do
+      parse
+
+      expect(@keep_alive).to eq(true)
     end
   end
 end
diff --git a/spec/integration/parser/response_parsing/introspection_spec.rb b/spec/integration/parser/response_parsing/introspection_spec.rb
index 0a57505..f8809ca 100644
--- a/spec/integration/parser/response_parsing/introspection_spec.rb
+++ b/spec/integration/parser/response_parsing/introspection_spec.rb
@@ -66,4 +66,20 @@ def on_headers_complete
       expect(@status_code).to eq(200)
     end
   end
+
+  describe "keep_alive" do
+    let(:extension) {
+      proc {
+        def on_headers_complete
+          @context.instance_variable_set(:@keep_alive, @context.instance.keep_alive?)
+        end
+      }
+    }
+
+    it "returns the keep alive state" do
+      parse
+
+      expect(@keep_alive).to eq(true)
+    end
+  end
 end