diff --git a/examples/typed_gen_server/lib/typed_gen_server/stage1.ex b/examples/typed_gen_server/lib/typed_gen_server/stage1.ex
index 0846ee92..4e6a41af 100644
--- a/examples/typed_gen_server/lib/typed_gen_server/stage1.ex
+++ b/examples/typed_gen_server/lib/typed_gen_server/stage1.ex
@@ -1,17 +1,20 @@
 defmodule TypedGenServer.Stage1.Server do
-  use GenServer
-  use GradualizerEx.TypeAnnotation
+  # use GenServer
+  use Gradient.TypeAnnotation
 
   ## Start IEx with:
   ##   iex -S mix run --no-start
   ##
+  ## Start Gradient:
+  ##   Application.ensure_all_started(:gradient)
+  ##
   ## Then use the following to recheck the file on any change:
-  ##   recompile(); GradualizerEx.type_check_file(:code.which( TypedGenServer.Stage1.Server ), [:infer])
+  ##   recompile(); Gradient.type_check_file(:code.which( TypedGenServer.Stage1.Server ), [:infer])
 
   ## Try switching between the definitions and see what happens
   @type message :: Contract.Echo.req() | Contract.Hello.req()
-  #@type message :: Contract.Echo.req()
-  #@type message :: {:echo_req, String.t()} | {:hello, String.t()}
+  # @type message :: Contract.Echo.req()
+  # @type message :: {:echo_req, String.t()} | {:hello, String.t()}
 
   @type state :: map()
 
@@ -20,19 +23,18 @@ defmodule TypedGenServer.Stage1.Server do
   end
 
   @spec echo(pid(), String.t()) :: String.t()
-  # @spec echo(pid(), String.t()) :: {:echo_req, String.t()}
   def echo(pid, message) do
-    case annotate_type( GenServer.call(pid, {:echo_req, message}), Contract.Echo.res() ) do
-    #case call_echo(pid, message) do
+    case annotate_type(GenServer.call(pid, {:echo_req, message}), Contract.Echo.res()) do
+      # case call_echo(pid, message) do
       ## Try changing the pattern or the returned response
       {:echo_res, response} -> response
     end
   end
 
-  #@spec call_echo(pid(), String.t()) :: Contract.Echo.res()
-  #defp call_echo(pid, message) do
+  # @spec call_echo(pid(), String.t()) :: Contract.Echo.res()
+  # defp call_echo(pid, message) do
   #  GenServer.call(pid, {:echo_req, message})
-  #end
+  # end
 
   @spec hello(pid(), String.t()) :: :ok
   def hello(pid, name) do
@@ -41,27 +43,25 @@ defmodule TypedGenServer.Stage1.Server do
     end
   end
 
-  @impl true
+  # @impl true
   def init(state) do
     {:ok, state}
   end
 
-  @impl true
-  def handle_call(m, from, state) do
-    {:noreply, handle(m, from, state)}
-  end
+  @type called(a) :: {:noreply, state()}
+                   | {:reply, a, state()}
 
-  @spec handle(message(), any, any) :: state()
+  # @impl true
+  @spec handle_call(message(), GenServer.from(), state())
+          :: called(Contract.Echo.res() | Contract.Hello.res())
   ## Try breaking the pattern match, e.g. by changing 'echo_req'
-  def handle({:echo_req, payload}, from, state) do
-    GenServer.reply(from, {:echo_res, payload})
-    state
+  def handle_call({:echo_req, payload}, _from, state) do
+    {:reply, {:echo_res, payload}, state}
   end
 
   ## Try commenting out the following clause
-  def handle({:hello, name}, from, state) do
+  def handle_call({:hello, name}, _from, state) do
     IO.puts("Hello, #{name}!")
-    GenServer.reply(from, :ok)
-    state
+    {:reply, :ok, state}
   end
 end
diff --git a/examples/typed_gen_server/lib/typed_gen_server/stage2.ex b/examples/typed_gen_server/lib/typed_gen_server/stage2.ex
index fe122a1e..f90b7b81 100644
--- a/examples/typed_gen_server/lib/typed_gen_server/stage2.ex
+++ b/examples/typed_gen_server/lib/typed_gen_server/stage2.ex
@@ -1,20 +1,23 @@
 defmodule TypedGenServer.Stage2.Server do
-  use GenServer
-  use GradualizerEx.TypeAnnotation
+  # use GenServer
+  use Gradient.TypeAnnotation
   alias Stage2.TypedServer
 
   ## Start IEx with:
   ##   iex -S mix run --no-start
   ##
+  ## Start Gradient:
+  ##   Application.ensure_all_started(:gradient)
+  ##
   ## Then use the following to recheck the file on any change:
-  ##   recompile(); GradualizerEx.type_check_file(:code.which( TypedGenServer.Stage2.Server ), [:infer])
+  ##   recompile(); Gradient.type_check_file(:code.which( TypedGenServer.Stage2.Server ), [:infer])
 
   @opaque t :: pid()
 
   ## Try switching between the definitions and see what happens
   @type message :: Contract.Echo.req() | Contract.Hello.req()
-  #@type message :: Contract.Echo.req()
-  #@type message :: {:echo_req, String.t()} | {:hello, String.t()}
+  # @type message :: Contract.Echo.req()
+  # @type message :: {:echo_req, String.t()} | {:hello, String.t()}
 
   @type state :: map()
 
@@ -24,10 +27,9 @@ defmodule TypedGenServer.Stage2.Server do
   end
 
   @spec echo(t(), String.t()) :: String.t()
-  # @spec echo(t(), String.t()) :: {:echo_req, String.t()}
   def echo(pid, message) do
-    case annotate_type( GenServer.call(pid, {:echo_req, message}), Contract.Echo.res() ) do
-    #case call_echo(pid, message) do
+    case annotate_type(GenServer.call(pid, {:echo_req, message}), Contract.Echo.res()) do
+      # case call_echo(pid, message) do
       ## Try changing the pattern or the returned response
       {:echo_res, response} -> response
     end
@@ -46,12 +48,12 @@ defmodule TypedGenServer.Stage2.Server do
     end
   end
 
-  @impl true
+  # @impl true
   def init(state) do
     {:ok, state}
   end
 
-  @impl true
+  # @impl true
   def handle_call(m, from, state) do
     {:noreply, handle(m, from, state)}
   end
@@ -62,8 +64,8 @@ defmodule TypedGenServer.Stage2.Server do
     ## This could register {:echo_req, payload} <-> {:echo_res, payload} mapping
     ## and response type at compile time to generate call_echo() automatically.
     ## Thanks Robert!
-    #TypedServer.reply( from, {:echo_res, payload}, Contract.Echo.res() )
-    GenServer.reply( from, {:echo_res, payload} )
+    # TypedServer.reply( from, {:echo_res, payload}, Contract.Echo.res() )
+    GenServer.reply(from, {:echo_res, payload})
     state
   end
 
@@ -78,15 +80,26 @@ end
 defmodule Test.TypedGenServer.Stage2.Server do
   alias TypedGenServer.Stage2.Server
 
+  ## Run with:
+  ##   recompile(); Test.TypedGenServer.Stage2.Server.test()
+  ##
   ## Typecheck with:
-  ##   recompile(); GradualizerEx.type_check_file(:code.which( Test.TypedGenServer.Stage2.Server ), [:infer])
+  ##   recompile(); Gradient.type_check_file(:code.which( Test.TypedGenServer.Stage2.Server ), [:infer])
+  ##   recompile(); Gradient.type_check_file(:code.which( Test.TypedGenServer.Stage2.Server ), [:infer, ex_check: false])
 
   @spec test :: any()
   def test do
     {:ok, srv} = Server.start_link()
-    pid = self()
+
+    pid =
+      spawn(fn ->
+        receive do
+          :unlikely -> :ok
+        end
+      end)
+
     "payload" = Server.echo(srv, "payload")
     ## This won't typecheck, since Server.echo only accepts Server.t(), that is our Server pids
-    #"payload" = Server.echo(pid, "payload")
+    # "payload" = Server.echo(pid, "payload")
   end
 end
diff --git a/examples/typed_gen_server/lib/typed_gen_server/stage3.ex b/examples/typed_gen_server/lib/typed_gen_server/stage3.ex
index 02023c74..5420af98 100644
--- a/examples/typed_gen_server/lib/typed_gen_server/stage3.ex
+++ b/examples/typed_gen_server/lib/typed_gen_server/stage3.ex
@@ -1,5 +1,4 @@
 defmodule Stage3.TypedServer do
-
   ## This doesn't play well with:
   ##   {:ok, srv} = MultiServer.start_link()
   ## Due to:
@@ -18,21 +17,21 @@ end
 
 defmodule TypedGenServer.Stage3.Server do
   use GenServer
-  use GradualizerEx.TypeAnnotation
+  use Gradient.TypeAnnotation
   alias Stage3.TypedServer
 
   ## Start IEx with:
   ##   iex -S mix run --no-start
   ##
   ## Then use the following to recheck the file on any change:
-  ##   recompile(); GradualizerEx.type_check_file(:code.which( TypedGenServer.Stage3.Server ), [:infer])
+  ##   recompile(); Gradient.type_check_file(:code.which( TypedGenServer.Stage3.Server ), [:infer])
 
   @opaque t :: {__MODULE__, pid()}
 
   ## Try switching between the definitions and see what happens
   @type message :: Contract.Echo.req() | Contract.Hello.req()
-  #@type message :: Contract.Echo.req()
-  #@type message :: {:echo_req, String.t()} | {:hello, String.t()}
+  # @type message :: Contract.Echo.req()
+  # @type message :: {:echo_req, String.t()} | {:hello, String.t()}
 
   @type state :: map()
 
@@ -44,17 +43,17 @@ defmodule TypedGenServer.Stage3.Server do
   @spec echo(t(), String.t()) :: String.t()
   # @spec echo(t(), String.t()) :: {:echo_req, String.t()}
   def echo(_server = {__MODULE__, _pid}, message) do
-    case annotate_type( GenServer.call(_pid, {:echo_req, message}), Contract.Echo.res() ) do
-    #case call_echo(_server, message) do
+    case annotate_type(GenServer.call(_pid, {:echo_req, message}), Contract.Echo.res()) do
+      # case call_echo(_server, message) do
       ## Try changing the pattern or the returned response
       {:echo_res, response} -> response
     end
   end
 
-  #@spec call_echo(t(), String.t()) :: Contract.Echo.res()
-  #defp call_echo({__MODULE__, pid}, message) do
+  # @spec call_echo(t(), String.t()) :: Contract.Echo.res()
+  # defp call_echo({__MODULE__, pid}, message) do
   #  GenServer.call(pid, {:echo_req, message})
-  #end
+  # end
 
   @spec hello(t(), String.t()) :: :ok
   def hello({__MODULE__, pid}, name) do
@@ -92,7 +91,7 @@ defmodule Test.TypedGenServer.Stage3.Server do
   alias TypedGenServer.Stage3.Server
 
   ## Typecheck with:
-  ##   recompile(); GradualizerEx.type_check_file(:code.which( Test.TypedGenServer.Stage3.Server ), [:infer])
+  ##   recompile(); Gradient.type_check_file(:code.which( Test.TypedGenServer.Stage3.Server ), [:infer])
 
   @spec test :: any()
   def test do
@@ -100,6 +99,6 @@ defmodule Test.TypedGenServer.Stage3.Server do
     pid = self()
     "payload" = Server.echo(srv, "payload")
     ## This won't typecheck, since Server.echo only accepts Server.t(), that is Server pids
-    #"payload" = Server.echo(pid, "payload")
+    # "payload" = Server.echo(pid, "payload")
   end
 end
diff --git a/examples/typed_gen_server/lib/typed_gen_server/stage4.ex b/examples/typed_gen_server/lib/typed_gen_server/stage4.ex
index 2ed12d42..baa56812 100644
--- a/examples/typed_gen_server/lib/typed_gen_server/stage4.ex
+++ b/examples/typed_gen_server/lib/typed_gen_server/stage4.ex
@@ -1,5 +1,5 @@
 defmodule TypedGenServer.Stage4.Server do
-  use GenServer
+  # use GenServer
   use Gradient.TypeAnnotation
   use Gradient.TypedServer
   alias Gradient.TypedServer
@@ -7,8 +7,12 @@ defmodule TypedGenServer.Stage4.Server do
   ## Start IEx with:
   ##   iex -S mix run --no-start
   ##
+  ## Start Gradient:
+  ##   Application.ensure_all_started(:gradient)
+  ##
   ## Then use the following to recheck the file on any change:
   ##   recompile(); Gradient.type_check_file(:code.which( TypedGenServer.Stage4.Server ), [:infer])
+  ##   recompile(); Gradient.type_check_file(:code.which( TypedGenServer.Stage4.Server ), [:infer, ex_check: false])
 
   @opaque t :: pid()
 
@@ -27,7 +31,7 @@ defmodule TypedGenServer.Stage4.Server do
   @spec echo(t(), String.t()) :: String.t()
   # @spec echo(t(), String.t()) :: {:echo_req, String.t()}
   def echo(pid, message) do
-    #case annotate_type(GenServer.call(pid, {:echo_req, message}), Contract.Echo.res()) do
+    # case annotate_type(GenServer.call(pid, {:echo_req, message}), Contract.Echo.res()) do
     case call_echo_req(pid, message) do
       ## Try changing the pattern or the returned response
       {:echo_res, response} -> response
@@ -38,22 +42,22 @@ defmodule TypedGenServer.Stage4.Server do
   ## thanks to using TypedServer.reply/3 instead of GenServer.reply/2.
   ## We don't have to define it!
   ## TODO: use the correct type instead of any as the second param!
-  #@spec call_echo_req(t(), any) :: Contract.Echo.res()
-  #defp call_echo_req(pid, message) do
+  # @spec call_echo_req(t(), any) :: Contract.Echo.res()
+  # defp call_echo_req(pid, message) do
   #  GenServer.call(pid, {:echo_req, message})
-  #end
+  # end
 
   @spec hello(t(), String.t()) :: :ok
   def hello(pid, name) do
     GenServer.call(pid, {:hello, name})
   end
 
-  @impl true
+  # @impl true
   def init(state) do
     {:ok, state}
   end
 
-  @impl true
+  # @impl true
   def handle_call(m, from, state) do
     {:noreply, handle(m, from, state)}
   end
@@ -64,11 +68,11 @@ defmodule TypedGenServer.Stage4.Server do
     ## TypedServer.reply/3 registers a {:echo_req, payload} <-> Contract.Echo.res() mapping
     ## and generates call_echo_req() at compile time.
     ## Thanks for the idea, @rvirding!
-    TypedServer.reply( from, {:echo_res, payload}, Contract.Echo.res() )
+    TypedServer.reply(from, {:echo_res, payload}, Contract.Echo.res())
     ## This will not typecheck - awesome!
-    #TypedServer.reply( from, {:invalid_tag, payload}, Contract.Echo.res() )
+    # TypedServer.reply( from, {:invalid_tag, payload}, Contract.Echo.res() )
     ## And this is the well known untyped equivalent.
-    #GenServer.reply(from, {:echo_res, payload})
+    # GenServer.reply(from, {:echo_res, payload})
     state
   end
 
@@ -85,13 +89,21 @@ defmodule Test.TypedGenServer.Stage4.Server do
 
   ## Typecheck with:
   ##   recompile(); Gradient.type_check_file(:code.which( Test.TypedGenServer.Stage4.Server ), [:infer])
+  ##   recompile(); Gradient.type_check_file(:code.which( Test.TypedGenServer.Stage4.Server ), [:infer, ex_check: false])
 
   @spec test :: any()
   def test do
     {:ok, srv} = Server.start_link()
-    pid = self()
+
+    pid =
+      spawn(fn ->
+        receive do
+          :unlikely -> :ok
+        end
+      end)
+
     "payload" = Server.echo(srv, "payload")
     ## This won't typecheck, since Server.echo only accepts Server.t(), that is our Server pids
-    #"payload" = Server.echo(pid, "payload")
+    # "payload" = Server.echo(pid, "payload")
   end
 end
diff --git a/examples/typed_gen_server/mix.exs b/examples/typed_gen_server/mix.exs
index fd9946b4..5c00fe3f 100644
--- a/examples/typed_gen_server/mix.exs
+++ b/examples/typed_gen_server/mix.exs
@@ -26,15 +26,14 @@ defmodule TypedGenServer.MixProject do
       {:gradient, path: "../../"},
       {:dialyxir, "~> 1.1", only: [:dev, :test], runtime: false},
       {:gradualizer,
-       github: "erszcz/Gradualizer", ref: "typed-gen-server", manager: :rebar3, override: true},
-      {:gradualizer_ex, github: "erszcz/gradualizer-ex", branch: "rs/wip"}
+       github: "erszcz/Gradualizer", ref: "typed-gen-server", manager: :rebar3, override: true}
     ]
   end
 
   defp dialyzer do
     [
       plt_add_deps: :app_tree,
-      #ignore_warnings: "dialyzer.ignore-warnings",
+      # ignore_warnings: "dialyzer.ignore-warnings",
       flags: ~w(
         error_handling
         race_conditions
@@ -43,5 +42,4 @@ defmodule TypedGenServer.MixProject do
       )a
     ]
   end
-
 end
diff --git a/examples/typed_gen_server/mix.lock b/examples/typed_gen_server/mix.lock
index 846fa08c..793b743f 100644
--- a/examples/typed_gen_server/mix.lock
+++ b/examples/typed_gen_server/mix.lock
@@ -1,6 +1,5 @@
 %{
   "dialyxir": {:hex, :dialyxir, "1.1.0", "c5aab0d6e71e5522e77beff7ba9e08f8e02bad90dfbeffae60eaf0cb47e29488", [:mix], [{:erlex, ">= 0.2.6", [hex: :erlex, repo: "hexpm", optional: false]}], "hexpm", "07ea8e49c45f15264ebe6d5b93799d4dd56a44036cf42d0ad9c960bc266c0b9a"},
   "erlex": {:hex, :erlex, "0.2.6", "c7987d15e899c7a2f34f5420d2a2ea0d659682c06ac607572df55a43753aa12e", [:mix], [], "hexpm", "2ed2e25711feb44d52b17d2780eabf998452f6efda104877a3881c2f8c0c0c75"},
-  "gradualizer": {:git, "https://github.com/erszcz/Gradualizer.git", "bd54184dae19d5117534c6e6885fa5abd1fe5da4", [ref: "typed-gen-server"]},
-  "gradualizer_ex": {:git, "https://github.com/erszcz/gradualizer-ex.git", "dc64f484c83a5ce286696fb79756577a1b9853f5", [branch: "rs/wip"]},
+  "gradualizer": {:git, "https://github.com/erszcz/Gradualizer.git", "764ddc6b4cc007008ea68eb9ec7a3f3adc2f1951", [ref: "typed-gen-server"]},
 }
diff --git a/lib/gradient/elixir_fmt.ex b/lib/gradient/elixir_fmt.ex
index 0be7abe7..00ebdac0 100644
--- a/lib/gradient/elixir_fmt.ex
+++ b/lib/gradient/elixir_fmt.ex
@@ -69,6 +69,39 @@ defmodule Gradient.ElixirFmt do
     format_expr_type_error(expression, actual_type, expected_type, opts)
   end
 
+  def format_type_error({:nonexhaustive, anno, example}, opts) do
+    formatted_example =
+      case example do
+        [x | xs] ->
+          :lists.foldl(
+            fn a, acc ->
+              [pp_expr(a, opts), "\n\t" | acc]
+            end,
+            [pp_expr(x, opts)],
+            xs
+          )
+          |> Enum.reverse()
+
+        x ->
+          pp_expr(x, opts)
+      end
+
+    :io_lib.format(
+      "~sNonexhaustive patterns~s~s",
+      [
+        format_location(anno, :brief, opts),
+        format_location(anno, :verbose, opts),
+        case :proplists.get_value(:fmt_location, opts, :verbose) do
+          :brief ->
+            :io_lib.format(": ~s\n", formatted_example)
+
+          :verbose ->
+            :io_lib.format("\nExample values which are not covered:~n\t~s~n", [formatted_example])
+        end
+      ]
+    )
+  end
+
   def format_type_error(
         {:spec_error, :wrong_spec_name, anno, name, arity},
         opts
diff --git a/lib/gradient/type_annotation.ex b/lib/gradient/type_annotation.ex
index 9028adc8..57d97a69 100644
--- a/lib/gradient/type_annotation.ex
+++ b/lib/gradient/type_annotation.ex
@@ -8,7 +8,7 @@ defmodule Gradient.TypeAnnotation do
   defp annotate(type_op, expr, type) do
     erlang_type = elixir_type_to_erlang(type)
     # IO.inspect(erlang_type, label: "erlang type")
-    {type_op, [], [expr, Macro.to_string(erlang_type)]}
+    {type_op, [], [expr, erlang_type]}
     # |> IO.inspect(label: "annotation node")
   end
 
diff --git a/lib/gradient/typed_server/compile_hooks.ex b/lib/gradient/typed_server/compile_hooks.ex
index 0cddbe1b..d2415f27 100644
--- a/lib/gradient/typed_server/compile_hooks.ex
+++ b/lib/gradient/typed_server/compile_hooks.ex
@@ -17,11 +17,6 @@ defmodule Gradient.TypedServer.CompileHooks do
   end
 
   def __on_definition__(env, _kind, name, args, _guards, body) do
-    if name == :handle do
-      # IO.inspect({name, env}, limit: :infinity)
-      IO.inspect({env.module, Module.get_attribute(env.module, :spec)})
-    end
-
     request_handler = Module.get_attribute(env.module, :request_handler, :handle)
 
     case request_handler do