diff --git a/lib/wafer/drivers/circuits/gpio.ex b/lib/wafer/drivers/circuits/gpio.ex
index e2b9288..b39521b 100644
--- a/lib/wafer/drivers/circuits/gpio.ex
+++ b/lib/wafer/drivers/circuits/gpio.ex
@@ -57,11 +57,11 @@ defimpl Wafer.GPIO, for: Wafer.Driver.Circuits.GPIO do
   import Wafer.Guards
 
   def read(%{ref: ref}) when is_reference(ref) do
-    case(Wrapper.read(ref)) do
+    case Wrapper.read(ref) do
       value when is_pin_value(value) -> {:ok, value}
-      {:error, reason} -> {:error, reason}
-      other -> {:error, "Invalid response from driver: #{inspect(other)}"}
     end
+  rescue
+    error -> {:error, error}
   end
 
   def write(%{ref: ref} = conn, value) when is_reference(ref) and is_pin_value(value) do
@@ -80,11 +80,11 @@ defimpl Wafer.GPIO, for: Wafer.Driver.Circuits.GPIO do
 
   def enable_interrupt(conn, pin_condition, metadata \\ nil)
       when is_pin_condition(pin_condition) do
-    with :ok <- Dispatcher.enable(conn, pin_condition, metadata), do: {:ok, conn}
+    Dispatcher.enable(conn, pin_condition, metadata)
   end
 
   def disable_interrupt(conn, pin_condition) when is_pin_condition(pin_condition) do
-    with :ok <- Dispatcher.disable(conn, pin_condition), do: {:ok, conn}
+    Dispatcher.disable(conn, pin_condition)
   end
 
   def pull_mode(%{ref: ref} = conn, mode) when is_reference(ref) and is_pin_pull_mode(mode) do
diff --git a/lib/wafer/drivers/circuits/i2c.ex b/lib/wafer/drivers/circuits/i2c.ex
index 6699ea6..c08cf7d 100644
--- a/lib/wafer/drivers/circuits/i2c.ex
+++ b/lib/wafer/drivers/circuits/i2c.ex
@@ -1,7 +1,7 @@
 defmodule Wafer.Driver.Circuits.I2C do
-  defstruct ~w[address bus ref]a
+  defstruct ~w[address bus conn]a
   @behaviour Wafer.Conn
-  alias Circuits.I2C.I2CDev
+  alias Circuits.I2C.Bus
   alias Wafer.Driver.Circuits.I2C.Wrapper
   alias Wafer.I2C
   import Wafer.Guards
@@ -12,7 +12,7 @@ defmodule Wafer.Driver.Circuits.I2C do
   Implements the `Wafer.Conn` behaviour as well as the `Wafer.Chip` and `Wafer.I2C` protocols.
   """
 
-  @type t :: %__MODULE__{address: I2C.address(), bus: binary, ref: reference}
+  @type t :: %__MODULE__{address: I2C.address(), bus: binary, conn: Bus.t()}
   @type options :: [option]
   @type option :: {:bus_name, binary} | {:address, I2C.address()} | {:force, boolean}
 
@@ -24,10 +24,10 @@ defmodule Wafer.Driver.Circuits.I2C do
   def acquire(opts) when is_list(opts) do
     with {:ok, bus} when is_binary(bus) <- Keyword.fetch(opts, :bus_name),
          {:ok, address} when is_i2c_address(address) <- Keyword.fetch(opts, :address),
-         {:ok, ref} when is_reference(ref) or is_struct(ref, I2CDev) <- Wrapper.open(bus),
-         devices when is_list(devices) <- Wrapper.detect_devices(ref),
+         {:ok, conn} <- Wrapper.open(bus),
+         devices when is_list(devices) <- Wrapper.detect_devices(conn),
          true <- Keyword.get(opts, :force, false) || Enum.member?(devices, address) do
-      {:ok, %__MODULE__{bus: bus, address: address, ref: ref}}
+      {:ok, %__MODULE__{bus: bus, address: address, conn: conn}}
     else
       false ->
         {:error, "No device detected at address. Pass `force: true` to override."}
@@ -49,24 +49,24 @@ defimpl Wafer.Release, for: Wafer.Driver.Circuits.I2C do
   Release all resources associated with this device.
   """
   @spec release(I2C.t()) :: :ok | {:error, reason :: any}
-  def release(%I2C{ref: ref} = _conn), do: Wrapper.close(ref)
+  def release(%I2C{conn: conn} = _conn), do: Wrapper.close(conn)
 end
 
 defimpl Wafer.Chip, for: Wafer.Driver.Circuits.I2C do
   alias Wafer.Driver.Circuits.I2C.Wrapper
   import Wafer.Guards
 
-  def read_register(%{ref: ref, address: address}, register_address, bytes)
+  def read_register(%{conn: conn, address: address}, register_address, bytes)
       when is_i2c_address(address) and is_register_address(register_address) and
              is_byte_size(bytes),
-      do: Wrapper.write_read(ref, address, <<register_address>>, bytes)
+      do: Wrapper.write_read(conn, address, <<register_address>>, bytes)
 
   def read_register(_conn, _register_address, _bytes), do: {:error, "Invalid argument"}
 
-  def write_register(%{ref: ref, address: address} = conn, register_address, data)
+  def write_register(%{conn: inner, address: address} = conn, register_address, data)
       when is_i2c_address(address) and is_register_address(register_address) and
              is_binary(data) do
-    with :ok <- Wrapper.write(ref, address, <<register_address, data::binary>>), do: {:ok, conn}
+    with :ok <- Wrapper.write(inner, address, <<register_address, data::binary>>), do: {:ok, conn}
   end
 
   def write_register(_conn, _register_address, _data), do: {:error, "Invalid argument"}
@@ -86,36 +86,35 @@ defimpl Wafer.I2C, for: Wafer.Driver.Circuits.I2C do
   import Wafer.Guards
   alias Wafer.Driver.Circuits.I2C.Wrapper
 
-  def read(%{ref: ref, address: address}, bytes, options \\ [])
+  def read(%{conn: conn, address: address}, bytes, options \\ [])
       when is_i2c_address(address) and is_byte_size(bytes) and
              is_list(options) do
-    case Wrapper.read(ref, address, bytes, options) do
+    case Wrapper.read(conn, address, bytes, options) do
       {:ok, data} when is_binary(data) and byte_size(data) == bytes -> {:ok, data}
       {:error, reason} -> {:error, reason}
       other -> {:error, "Invalid response from driver: #{inspect(other)}"}
     end
   end
 
-  def write(%{ref: ref, address: address} = conn, data, options \\ [])
+  def write(%{conn: inner, address: address} = conn, data, options \\ [])
       when is_i2c_address(address) and is_binary(data) and is_list(options) do
-    with :ok <- Wrapper.write(ref, address, data, options), do: {:ok, conn}
+    with :ok <- Wrapper.write(inner, address, data, options), do: {:ok, conn}
   end
 
-  def write_read(%{ref: ref, address: address} = conn, data, bytes, options \\ [])
+  def write_read(%{conn: inner, address: address} = conn, data, bytes, options \\ [])
       when is_i2c_address(address) and is_binary(data) and
              is_byte_size(bytes) and is_list(options) do
-    case Wrapper.write_read(ref, address, data, bytes, options) do
+    case Wrapper.write_read(inner, address, data, bytes, options) do
       {:ok, data} when is_binary(data) and byte_size(data) == bytes -> {:ok, data, conn}
       {:error, reason} -> {:error, reason}
       other -> {:error, "Invalid response from driver: #{inspect(other)}"}
     end
   end
 
-  def detect_devices(%{ref: ref}) when is_reference(ref) do
-    case Wrapper.detect_devices(ref) do
+  def detect_devices(%{conn: conn}) do
+    case Wrapper.detect_devices(conn) do
       devices when is_list(devices) -> {:ok, devices}
       {:error, reason} -> {:error, reason}
-      other -> {:error, "Invalid response from driver: #{inspect(other)}"}
     end
   end
 end
diff --git a/lib/wafer/drivers/elixir_ale/i2c.ex b/lib/wafer/drivers/elixir_ale/i2c.ex
index 271a578..8edc1c8 100644
--- a/lib/wafer/drivers/elixir_ale/i2c.ex
+++ b/lib/wafer/drivers/elixir_ale/i2c.ex
@@ -115,7 +115,6 @@ defimpl Wafer.I2C, for: Wafer.Driver.ElixirALE.I2C do
     case Wrapper.detect_devices(pid) do
       devices when is_list(devices) -> {:ok, devices}
       {:error, reason} -> {:error, reason}
-      other -> {:error, "Invalid response from driver: #{inspect(other)}"}
     end
   end
 end
diff --git a/lib/wafer/drivers/fake.ex b/lib/wafer/drivers/fake.ex
index b91374e..8b243f3 100644
--- a/lib/wafer/drivers/fake.ex
+++ b/lib/wafer/drivers/fake.ex
@@ -87,7 +87,7 @@ defimpl Wafer.I2C, for: Wafer.Driver.Fake do
     {:ok, <<0::size(bits)>>, conn}
   end
 
-  def detect_devices(_conn), do: []
+  def detect_devices(_conn), do: {:ok, []}
 end
 
 defimpl Wafer.SPI, for: Wafer.Driver.Fake do
diff --git a/lib/wafer/i2c.ex b/lib/wafer/i2c.ex
index 0bceb7c..4961ecd 100644
--- a/lib/wafer/i2c.ex
+++ b/lib/wafer/i2c.ex
@@ -63,7 +63,7 @@ defprotocol Wafer.I2C do
   @doc """
   Detect the devices adjacent to the connection's device on the same I2C bus.
   """
-  @spec detect_devices(Conn.t()) :: {:ok, [address]}
+  @spec detect_devices(Conn.t()) :: {:ok, [address]} | {:error, any}
   def detect_devices(conn)
 end
 
diff --git a/lib/wafer/release.ex b/lib/wafer/release.ex
index 77dd796..724355e 100644
--- a/lib/wafer/release.ex
+++ b/lib/wafer/release.ex
@@ -30,7 +30,7 @@ defprotocol Wafer.Release do
   Release all resources associated with the connection.  Usually in preparation
   for shutdown.
   """
-  @spec release(Conn.t()) :: :ok
+  @spec release(Conn.t()) :: :ok | {:error, any}
   def release(conn)
 end
 
diff --git a/lib/wafer/twiddles.ex b/lib/wafer/twiddles.ex
index 529ed24..1256616 100644
--- a/lib/wafer/twiddles.ex
+++ b/lib/wafer/twiddles.ex
@@ -173,7 +173,7 @@ defmodule Wafer.Twiddles do
       iex> find_ones(<<0x0A>>)
       [1, 3]
   """
-  @spec find_ones(byte | single_byte_binary) :: non_neg_integer
+  @spec find_ones(byte | single_byte_binary) :: [non_neg_integer]
   def find_ones(byte) when is_byte(byte) do
     0..7
     |> Enum.filter(&(get_bit(byte, &1) == 1))
@@ -192,7 +192,7 @@ defmodule Wafer.Twiddles do
       iex> find_zeroes(<<0xFA>>)
       [0, 2]
   """
-  @spec find_zeroes(byte | single_byte_binary) :: non_neg_integer
+  @spec find_zeroes(byte | single_byte_binary) :: [non_neg_integer]
   def find_zeroes(byte) when is_byte(byte) do
     0..7
     |> Enum.filter(&(get_bit(byte, &1) == 0))
diff --git a/mix.exs b/mix.exs
index 02208d3..1d7c5dc 100644
--- a/mix.exs
+++ b/mix.exs
@@ -56,6 +56,7 @@ defmodule Wafer.MixProject do
 
       # Dev/test
       {:credo, "~> 1.6", devtest},
+      {:dialyxir, "~> 1.4", devtest},
       {:earmark, "~> 1.4", devtest},
       {:ex_check, "~> 0.15", devtest},
       {:ex_doc, ">= 0.0.0", devtest},
diff --git a/mix.lock b/mix.lock
index cb12569..ecb9156 100644
--- a/mix.lock
+++ b/mix.lock
@@ -1,13 +1,15 @@
 %{
   "bunt": {:hex, :bunt, "0.2.1", "e2d4792f7bc0ced7583ab54922808919518d0e57ee162901a16a1b6664ef3b14", [:mix], [], "hexpm", "a330bfb4245239787b15005e66ae6845c9cd524a288f0d141c148b02603777a5"},
   "circuits_gpio": {:hex, :circuits_gpio, "1.0.0", "b2a493b1822ec712bfba7068a016930f6db5e31713b9b84ed8bc307c7c323682", [:make, :mix], [{:elixir_make, "~> 0.6", [hex: :elixir_make, repo: "hexpm", optional: false]}], "hexpm", "da64c1d9ba1329cd7ca7e63adcd68d73e2294d6b48eb66c9a1064f3db5c523f3"},
-  "circuits_i2c": {:hex, :circuits_i2c, "2.0.0", "8343b12879189f844835abeaf31a36c5626b8ace58413a582794fdfe60c2dc0e", [:make, :mix], [{:elixir_make, "~> 0.6", [hex: :elixir_make, repo: "hexpm", optional: false]}], "hexpm", "06eccd33b36bcedf41730cac8da58e359967ea63a2cd899cea58c2a138634cc4"},
+  "circuits_i2c": {:hex, :circuits_i2c, "2.0.1", "e9ab22f078b403cafd2c5006fff448f9a790f73c04e9135b7ac22f45f2e63c5c", [:make, :mix], [{:elixir_make, "~> 0.6", [hex: :elixir_make, repo: "hexpm", optional: false]}], "hexpm", "a1567004389b49637fe34d9dd8bdf36c26a53c269e654753860b5c09532bc3c4"},
   "circuits_spi": {:hex, :circuits_spi, "1.3.0", "d66d4c8818739416958cea1d846d66896ab7c28fa42695f1cae3c2c7a3e9e9ca", [:make, :mix], [{:elixir_make, "~> 0.6", [hex: :elixir_make, repo: "hexpm", optional: false]}], "hexpm", "56e49b346fdd43185832a03d3de3751c2ce9928ee3ce4a31a364f6548fe2b74c"},
   "credo": {:hex, :credo, "1.7.1", "6e26bbcc9e22eefbff7e43188e69924e78818e2fe6282487d0703652bc20fd62", [:mix], [{:bunt, "~> 0.2.1", [hex: :bunt, repo: "hexpm", optional: false]}, {:file_system, "~> 0.2.8", [hex: :file_system, repo: "hexpm", optional: false]}, {:jason, "~> 1.0", [hex: :jason, repo: "hexpm", optional: false]}], "hexpm", "e9871c6095a4c0381c89b6aa98bc6260a8ba6addccf7f6a53da8849c748a58a2"},
+  "dialyxir": {:hex, :dialyxir, "1.4.2", "764a6e8e7a354f0ba95d58418178d486065ead1f69ad89782817c296d0d746a5", [:mix], [{:erlex, ">= 0.2.6", [hex: :erlex, repo: "hexpm", optional: false]}], "hexpm", "516603d8067b2fd585319e4b13d3674ad4f314a5902ba8130cd97dc902ce6bbd"},
   "earmark": {:hex, :earmark, "1.4.19", "3854a17305c880cc46305af15fb1630568d23a709aba21aaa996ced082fc29d7", [:mix], [{:earmark_parser, ">= 1.4.18", [hex: :earmark_parser, repo: "hexpm", optional: false]}], "hexpm", "d5a8c9f9e37159a8fdd3ea8437fb4e229eaf56d5129b9a011dc4780a4872079d"},
   "earmark_parser": {:hex, :earmark_parser, "1.4.19", "de0d033d5ff9fc396a24eadc2fcf2afa3d120841eb3f1004d138cbf9273210e8", [:mix], [], "hexpm", "527ab6630b5c75c3a3960b75844c314ec305c76d9899bb30f71cb85952a9dc45"},
   "elixir_ale": {:hex, :elixir_ale, "1.2.1", "07ac2f17a0191b8bd3b0df6b526c7f699a3a4d690c9def573fcb5824eef24d98", [:make, :mix], [{:elixir_make, "~> 0.4", [hex: :elixir_make, repo: "hexpm", optional: false]}], "hexpm", "bfb099137500a3b8c4a1750cf07f2d704897ef9feac3412064bf9edc7d74193c"},
   "elixir_make": {:hex, :elixir_make, "0.7.7", "7128c60c2476019ed978210c245badf08b03dbec4f24d05790ef791da11aa17c", [:mix], [{:castore, "~> 0.1 or ~> 1.0", [hex: :castore, repo: "hexpm", optional: true]}], "hexpm", "5bc19fff950fad52bbe5f211b12db9ec82c6b34a9647da0c2224b8b8464c7e6c"},
+  "erlex": {:hex, :erlex, "0.2.6", "c7987d15e899c7a2f34f5420d2a2ea0d659682c06ac607572df55a43753aa12e", [:mix], [], "hexpm", "2ed2e25711feb44d52b17d2780eabf998452f6efda104877a3881c2f8c0c0c75"},
   "ex_check": {:hex, :ex_check, "0.15.0", "074b94c02de11c37bba1ca82ae5cc4926e6ccee862e57a485b6ba60fca2d8dc1", [:mix], [], "hexpm", "33848031a0c7e4209c3b4369ce154019788b5219956220c35ca5474299fb6a0e"},
   "ex_doc": {:hex, :ex_doc, "0.28.1", "34fab7e7201c5a1f275f3b2f837125c940c512e8543d181bd4dd7acb19c8dba0", [:mix], [{:earmark_parser, "~> 1.4.19", [hex: :earmark_parser, repo: "hexpm", optional: false]}, {:makeup_elixir, "~> 0.14", [hex: :makeup_elixir, repo: "hexpm", optional: false]}, {:makeup_erlang, "~> 0.1", [hex: :makeup_erlang, repo: "hexpm", optional: false]}], "hexpm", "10e564dd59101a5edc4de7009a54baed015a246dee01f7200aab24e8f57fc044"},
   "file_system": {:hex, :file_system, "0.2.10", "fb082005a9cd1711c05b5248710f8826b02d7d1784e7c3451f9c1231d4fc162d", [:mix], [], "hexpm", "41195edbfb562a593726eda3b3e8b103a309b733ad25f3d642ba49696bf715dc"},
diff --git a/test/drivers/circuits_gpio_test.exs b/test/drivers/circuits_gpio_test.exs
index 43e42d9..2ab4dd8 100644
--- a/test/drivers/circuits_gpio_test.exs
+++ b/test/drivers/circuits_gpio_test.exs
@@ -101,7 +101,7 @@ defmodule WaferDriverCircuits.GPIOTest do
       |> expect(:enable, 1, fn conn1, pin_condition, _metadata ->
         assert conn1 == conn
         assert pin_condition == :rising
-        :ok
+        {:ok, conn1}
       end)
 
       assert {:ok, ^conn} = GPIO.enable_interrupt(conn, :rising)
@@ -116,7 +116,7 @@ defmodule WaferDriverCircuits.GPIOTest do
       |> expect(:disable, 1, fn conn1, pin_condition ->
         assert conn1 == conn
         assert pin_condition == :rising
-        :ok
+        {:ok, conn1}
       end)
 
       assert {:ok, ^conn} = GPIO.disable_interrupt(conn, :rising)
diff --git a/test/drivers/circuits_i2c_test.exs b/test/drivers/circuits_i2c_test.exs
index 85dd95e..8bfc624 100644
--- a/test/drivers/circuits_i2c_test.exs
+++ b/test/drivers/circuits_i2c_test.exs
@@ -77,7 +77,7 @@ defmodule WaferCircuits.I2CTest do
 
       Wrapper
       |> expect(:close, 1, fn ref ->
-        assert ref == conn.ref
+        assert ref == conn.conn
         :ok
       end)
 
@@ -91,7 +91,7 @@ defmodule WaferCircuits.I2CTest do
 
       Wrapper
       |> expect(:write_read, 1, fn ref, addr, data, bytes ->
-        assert ref == conn.ref
+        assert ref == conn.conn
         assert addr == conn.address
         assert data == <<0>>
         assert bytes == 2
@@ -108,7 +108,7 @@ defmodule WaferCircuits.I2CTest do
 
       Wrapper
       |> expect(:write, 1, fn ref, addr, data ->
-        assert ref == conn.ref
+        assert ref == conn.conn
         assert addr == conn.address
         assert data == <<1, 2, 3>>
         :ok
@@ -124,7 +124,7 @@ defmodule WaferCircuits.I2CTest do
 
       Wrapper
       |> expect(:write_read, 1, fn ref, addr, data, bytes ->
-        assert ref == conn.ref
+        assert ref == conn.conn
         assert addr == conn.address
         assert data == <<0>>
         assert bytes == 2
@@ -133,7 +133,7 @@ defmodule WaferCircuits.I2CTest do
 
       Wrapper
       |> expect(:write, 1, fn ref, addr, data ->
-        assert ref == conn.ref
+        assert ref == conn.conn
         assert addr == conn.address
         assert data == <<0, 1, 1>>
         :ok
@@ -149,7 +149,7 @@ defmodule WaferCircuits.I2CTest do
 
       Wrapper
       |> expect(:read, 1, fn ref, addr, bytes, opts ->
-        assert ref == conn.ref
+        assert ref == conn.conn
         assert addr == conn.address
         assert bytes == 2
         assert opts == []
@@ -166,7 +166,7 @@ defmodule WaferCircuits.I2CTest do
 
       Wrapper
       |> expect(:write, 1, fn ref, addr, data, opts ->
-        assert ref == conn.ref
+        assert ref == conn.conn
         assert addr == conn.address
         assert data == <<0, 0>>
         assert opts == []
@@ -183,7 +183,7 @@ defmodule WaferCircuits.I2CTest do
 
       Wrapper
       |> expect(:write_read, 1, fn ref, addr, data, bytes, opts ->
-        assert ref == conn.ref
+        assert ref == conn.conn
         assert addr == conn.address
         assert data == <<1>>
         assert bytes == 2
@@ -202,7 +202,7 @@ defmodule WaferCircuits.I2CTest do
 
       Wrapper
       |> expect(:detect_devices, 1, fn ref ->
-        assert conn.ref == ref
+        assert conn.conn == ref
         [conn.address]
       end)
 
@@ -210,5 +210,5 @@ defmodule WaferCircuits.I2CTest do
     end
   end
 
-  defp conn, do: %Subject{ref: :erlang.make_ref(), bus: "i2c-1", address: 0x13}
+  defp conn, do: %Subject{conn: :erlang.make_ref(), bus: "i2c-1", address: 0x13}
 end