diff --git a/lib/wootheex.ex b/lib/wootheex.ex
index a79a3ea..1b9b18e 100644
--- a/lib/wootheex.ex
+++ b/lib/wootheex.ex
@@ -1,52 +1,3 @@
-defmodule Wootheex.UserAgent do
-  alias Wootheex, as: W
-  @type parse_result_explicit :: %__MODULE__{
-    category: W.category,
-    browser_name: W.browser_name,
-    browser_type: W.browser_type,
-    browser_version: W.browser_version,
-    os: W.os,
-    os_version: W.os_version,
-    vendor: W.vendor
-  }
-  @enforce_keys [:category, :browser_name, :browser_type, :browser_version, :os, :os_version, :vendor]
-  defstruct @enforce_keys
-
-  @doc """
-  Parse user agent to a struct
-
-      iex> Wootheex.UserAgent.parse "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_10_4) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/44.0.2403.155 Safari/537.36"
-      %Wootheex.UserAgent{
-        browser_name: "Chrome",
-        browser_type: :browser,
-        browser_version: "44.0.2403.155",
-        category: :pc,
-        os: "Mac OSX",
-        os_version: "10.10.4",
-        vendor: "Google"
-      }
-
-  """
-  @spec parse(W.user_agent) :: parse_result_explicit
-  def parse(ua) do
-    info = W.parse(ua)
-    {cat, bname, btype, bver, os, osver, vendor} =
-      case info do
-        :other -> {:other, :other, :other, :other, :other, :other, :other}
-        t when is_tuple(t) -> t
-      end
-    %__MODULE__{
-      category: cat,
-      browser_name: bname,
-      browser_type: btype,
-      browser_version: bver,
-      os: os,
-      os_version: osver,
-      vendor: vendor
-    }
-  end
-end
-
 defmodule Wootheex do
   @type user_agent :: binary
 
@@ -79,7 +30,13 @@ defmodule Wootheex do
   app = Mix.Project.config[:app]
 
   def load_dynlib() do
-    path = :filename.join([:code.priv_dir(unquote(app)), 'native', 'libwootheex_nif'])
-    :ok = :erlang.load_nif(path, 0)
+    :ok = 
+      [:code.priv_dir(unquote(app)), 'native', 'libwootheex_nif']
+      |> :filename.join()
+      |> :erlang.load_nif(0)
   end
 end
+
+defmodule WootheexError do
+  defexception [:message]
+end
diff --git a/lib/wootheex/user_agent.ex b/lib/wootheex/user_agent.ex
new file mode 100644
index 0000000..d5d1679
--- /dev/null
+++ b/lib/wootheex/user_agent.ex
@@ -0,0 +1,89 @@
+defmodule Wootheex.UserAgent do
+
+  @type t :: %__MODULE__{
+    category:        Wootheex.category(),
+    browser_name:    Wootheex.browser_name(),
+    browser_type:    Wootheex.browser_type(),
+    browser_version: Wootheex.browser_version(),
+    os:              Wootheex.os(),
+    os_version:      Wootheex.os_version(),
+    vendor:          Wootheex.vendor()
+  }
+  @enforce_keys [
+    :category,
+    :browser_name,
+    :browser_type,
+    :browser_version,
+    :os,
+    :os_version,
+    :vendor
+  ]
+  defstruct @enforce_keys
+
+  @doc """
+  Parse user agent to a struct or raises an error
+
+      iex> Wootheex.UserAgent.parse! "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_10_4) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/44.0.2403.155 Safari/537.36"
+      %Wootheex.UserAgent{
+        browser_name: "Chrome",
+        browser_type: :browser,
+        browser_version: "44.0.2403.155",
+        category: :pc,
+        os: "Mac OSX",
+        os_version: "10.10.4",
+        vendor: "Google"
+      }
+
+  """
+  @spec parse!(Wootheex.user_agent) :: t()
+  def parse!(ua) do
+    case Wootheex.parse(ua) do
+      :other -> raise WootheexError, "unknown user agent"
+      {cat, bname, btype, bver, os, osver, vendor} ->
+        %__MODULE__{
+          category: cat,
+          browser_name: bname,
+          browser_type: btype,
+          browser_version: bver,
+          os: os,
+          os_version: osver,
+          vendor: vendor
+        }
+    end
+  end
+
+  @doc """
+  Safely parses user agent to a struct
+
+      iex> Wootheex.UserAgent.parse "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_10_4) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/44.0.2403.155 Safari/537.36"
+      {:ok,
+        %Wootheex.UserAgent{
+          browser_name: "Chrome",
+          browser_type: :browser,
+          browser_version: "44.0.2403.155",
+          category: :pc,
+          os: "Mac OSX",
+          os_version: "10.10.4",
+          vendor: "Google"
+        }
+      }
+  """
+  @spec parse(Wootheex.user_agent) :: {:ok, t()} | {:error, any()}
+  def parse(ua) do
+    case Wootheex.parse(ua) do
+      :other -> {:error, "unknown user agent"}
+      {cat, bname, btype, bver, os, osver, vendor} ->
+        {:ok,
+          %__MODULE__{
+            category: cat,
+            browser_name: bname,
+            browser_type: btype,
+            browser_version: bver,
+            os: os,
+            os_version: osver,
+            vendor: vendor
+          }
+        }
+    end
+  end
+end
diff --git a/test/wootheex_test.exs b/test/wootheex_test.exs
index 3abcbcd..5924f84 100644
--- a/test/wootheex_test.exs
+++ b/test/wootheex_test.exs
@@ -3,15 +3,18 @@ defmodule WootheexTest do
   doctest Wootheex
   doctest Wootheex.UserAgent
 
-  alias Wootheex, as: W
-
   test "Invalid argument (integer)" do
     number = 42
-    assert_raise ArgumentError, fn -> assert W.parse(number) end
+    assert_raise ArgumentError, fn -> assert Wootheex.parse(number) end
   end
 
   test "Invalid UTF-8" do
     invalid_string = <<255, 1>>
-    assert_raise ArgumentError, fn -> assert W.parse(invalid_string) end
+    assert_raise ArgumentError, fn -> assert Wootheex.parse(invalid_string) end
+  end
+
+  test "Invalid UserAgent" do
+    ua = "blahblahblahblahblahblahblahblahblah"
+    assert_raise WootheexError, fn -> assert Wootheex.UserAgent.parse!(ua) end
   end
 end