diff --git a/lib/zig/error_prong.ex b/lib/zig/error_prong.ex
index 0608bba5..ae8c58ee 100644
--- a/lib/zig/error_prong.ex
+++ b/lib/zig/error_prong.ex
@@ -4,7 +4,7 @@ defmodule Zig.ErrorProng do
 
   # default parameter errors handling.
 
-  def argument_error_prong(:elixir, _) do
+  def argument_error_prong(:elixir) do
     quote do
       :error, {:argument_error, index, error_lines} ->
         new_stacktrace =
@@ -61,7 +61,7 @@ defmodule Zig.ErrorProng do
     end
   end
 
-  def argument_error_prong(:erlang, _) do
+  def argument_error_prong(:erlang) do
     [
       "error:{error, badarg, _ExtraStacktrace}:Stacktrace -> erlang:raise(error, badarg, Stacktrace)"
     ]
diff --git a/lib/zig/nif.ex b/lib/zig/nif.ex
index c8d7dad3..7e4b1c92 100644
--- a/lib/zig/nif.ex
+++ b/lib/zig/nif.ex
@@ -161,6 +161,18 @@ defmodule Zig.Nif do
   #  end
   # end
 
+  # COMMON TOOLS
+  # generates AST for parameters.  
+  @spec elixir_parameters(arity, used :: boolean) :: [Macro.t]
+  def elixir_parameters(0, _), do: []
+  def elixir_parameters(arity, true), do: Enum.map(1..arity, &{:"arg#{&1}", [], Elixir})
+  def elixir_parameters(arity, false), do: Enum.map(1..arity, &{:"_arg#{&1}", [], Elixir})
+
+  @spec erlang_parameters(arity, used :: boolean) :: [{:var, atom()}]
+  def erlang_parameters(0, _), do: []
+  def erlang_parameters(arity, true), do: Enum.map(1..arity, &{:var, :"X#{&1}"})
+  def erlang_parameters(arity, false), do: Enum.map(1..arity, &{:var, :"_X#{&1}"})
+
   # Access behaviour guards
   @impl true
   def get_and_update(_, _, _), do: raise("you should not update a function")
diff --git a/lib/zig/nif/_basic.ex b/lib/zig/nif/_basic.ex
index 5e3a48e6..d8c6e5f4 100644
--- a/lib/zig/nif/_basic.ex
+++ b/lib/zig/nif/_basic.ex
@@ -16,14 +16,28 @@ defmodule Zig.Nif.Basic do
   alias Zig.Nif.DirtyIo
   alias Zig.Nif.Synchronous
   alias Zig.Type
+  alias Zig.Type.Integer
 
   import Zig.QuoteErl
 
   # marshalling setup
+  #
+  # for a basic function, a marshalling function is required unless the function ONLY
+  # has term or erl_nif_term parameters, because those parameters may emit `argumenterror`
+  # which needs to be trapped and converted.
+  #
+  # returning a value cannot error so they do not need to be marshalled, except for
+  # integers of size greater than 64 bits.
+
+  defp marshals_param?(:term), do: false
+  defp marshals_param?(:erl_nif_term), do: false
+  defp marshals_param?(_), do: true
+
+  defp marshals_return?(%Integer{bits: bits}), do: bits > 64
+  defp marshals_return?(_), do: false
 
   defp needs_marshal?(nif) do
-    Enum.any?(nif.signature.params, &Type.marshals_param?/1) or
-      Type.marshals_return?(nif.signature.return)
+    Enum.any?(nif.signature.params, &marshals_param?/1) or marshals_return?(nif.signature.return)
   end
 
   defp marshal_name(nif), do: :"marshalled-#{nif.name}"
@@ -33,26 +47,16 @@ defmodule Zig.Nif.Basic do
   end
 
   def render_elixir(%{signature: signature} = nif) do
-    {empty_params, used_params} =
-      case signature.arity do
-        0 ->
-          {[], []}
-
-        n ->
-          1..n
-          |> Enum.map(&{{:"_arg#{&1}", [], Elixir}, {:"arg#{&1}", [], Elixir}})
-          |> Enum.unzip()
-      end
-
     error_text = "nif for function #{signature.name}/#{signature.arity} not bound"
 
     def_or_defp = if nif.export, do: :def, else: :defp
 
     if needs_marshal?(nif) do
-      render_elixir_marshalled(nif, def_or_defp, empty_params, used_params, error_text)
+      render_elixir_marshalled(nif, def_or_defp, signature.arity, error_text)
     else
+      unused_params = Nif.elixir_parameters(signature.arity, false)
       quote context: Elixir do
-        unquote(def_or_defp)(unquote(signature.name)(unquote_splicing(empty_params))) do
+        unquote(def_or_defp)(unquote(signature.name)(unquote_splicing(unused_params))) do
           :erlang.nif_error(unquote(error_text))
         end
       end
@@ -62,10 +66,13 @@ defmodule Zig.Nif.Basic do
   defp render_elixir_marshalled(
          %{signature: signature} = nif,
          def_or_defp,
-         empty_params,
-         used_params,
+         arity,
          error_text
        ) do
+
+    used_params = Nif.elixir_parameters(signature.arity, true)
+    unused_params = Nif.elixir_parameters(signature.arity, false)
+
     marshal_name = marshal_name(nif)
 
     marshal_params =
@@ -74,7 +81,7 @@ defmodule Zig.Nif.Basic do
       |> Enum.with_index()
       |> Enum.flat_map(fn {{param_type, param}, index} ->
         List.wrap(
-          if Type.marshals_param?(param_type) do
+          if marshals_param?(param_type) do
             Type.marshal_param(param_type, param, index, :elixir)
           end
         )
@@ -86,20 +93,35 @@ defmodule Zig.Nif.Basic do
       end
 
     marshal_return =
-      if Type.marshals_return?(signature.return) do
+      if marshals_return?(signature.return) do
         Type.marshal_return(signature.return, return, :elixir)
       else
         return
       end
 
+    function_code = [do: quote do
+      unquote_splicing(marshal_params)
+      return = unquote(marshal_name)(unquote_splicing(used_params))
+      unquote(marshal_return)
+    end]
+
+    argument_error_prong = List.wrap(if true do
+      Zig.ErrorProng.argument_error_prong(:elixir)
+    end)
+
+    error_return_prong = []
+
+    error_prongs = case {argument_error_prong, error_return_prong} do
+      {[], []} -> []
+      _ -> [catch: argument_error_prong ++ error_return_prong]
+    end
+
+    function_block = function_code ++ error_prongs
+
     quote do
-      unquote(def_or_defp)(unquote(nif.name)(unquote_splicing(used_params))) do
-        unquote_splicing(marshal_params)
-        return = unquote(marshal_name)(unquote_splicing(used_params))
-        unquote(marshal_return)
-      end
+      unquote(def_or_defp)(unquote(nif.name)(unquote_splicing(used_params)), unquote(function_block))
 
-      defp unquote(marshal_name)(unquote_splicing(empty_params)) do
+      defp unquote(marshal_name)(unquote_splicing(unused_params)) do
         :erlang.nif_error(unquote(error_text))
       end
     end
@@ -124,7 +146,7 @@ defmodule Zig.Nif.Basic do
         type.params
         |> Enum.zip(used_vars)
         |> Enum.map_reduce([], fn {param_type, {:var, var}}, so_far ->
-          if Type.marshals_param?(param_type) do
+          if marshals_param?(param_type) do
             {{:var, :"#{var}_m"}, [so_far, Type.marshal_param(param_type, var, nil, :erlang)]}
           else
             {{:var, var}, so_far}
@@ -132,7 +154,7 @@ defmodule Zig.Nif.Basic do
         end)
 
       result_code =
-        if Type.marshals_param?(type.return) do
+        if marshals_param?(type.return) do
           Type.marshal_return(type.return, :Result, :erlang)
         else
           "Result"
diff --git a/lib/zig/templates/basic.zig.eex b/lib/zig/templates/basic.zig.eex
index 77a98bed..ae6a3a37 100644
--- a/lib/zig/templates/basic.zig.eex
+++ b/lib/zig/templates/basic.zig.eex
@@ -22,7 +22,7 @@ fn <%= @name %>(env: beam.env, argc: c_int, args: [*c] const e.ErlNifTerm) callc
         var error_index: u8 = undefined;
 
         const payload = beam.payload.build(nif.<%= @name %>, argc, args, &error_index, payload_opts) catch |err| {
-            return e.enif_raise_exception(env, beam.make(.{err, error_index, beam.make_empty_list(.{})}, .{}).v);
+            return e.enif_raise_exception(env, beam.make(.{err, error_index, error_info}, .{}).v);
         };
 
         // defer beam.payload.cleanup(payload, cleanup_opts);
diff --git a/lib/zig/type.ex b/lib/zig/type.ex
index 4c767157..5c5b2cfa 100644
--- a/lib/zig/type.ex
+++ b/lib/zig/type.ex
@@ -14,19 +14,14 @@ defprotocol Zig.Type do
   alias Zig.Type.Resource
 
   @type t ::
-          Bool.t() | Enum.t() | Float.t() | Integer.t() | Struct.t() | :env | :pid | :port | :term
-
-  @spec marshals_param?(t) :: boolean
-  @doc "beam-side type conversions that might be necessary to get an elixir parameter into a zig parameter"
-  def marshals_param?(type)
+          Array.t() | Bool.t() | Cpointer.t() | Error.t() | Zig.Type.Enum.t() | Float.t() | 
+          Integer.t() | ManyPointer.t() | Optional.t() | Slice.t() | Struct.t() | :void | 
+          :anyopaque_pointer | :env | :pid | :port | :term | :erl_nif_term | :erl_nif_binary |
+          :erl_nif_event | :erl_nif_binary_pointer | :stacktrace
 
   @spec marshal_param(t, Macro.t(), non_neg_integer, :elixir | :erlang) :: Macro.t()
   def marshal_param(type, variable, index, platform)
 
-  @spec marshals_return?(t) :: boolean
-  @doc "beam-side type conversions that might be necessary to get a zig return into an elixir return"
-  def marshals_return?(type)
-
   @spec marshal_return(t, Macro.t(), Elixir | :erlang) :: Macro.t()
   def marshal_return(type, variable, platform)
 
@@ -230,17 +225,12 @@ after
 
   def _default_payload_options, do: ".{.error_info = &error_info},"
   def _default_return, do: "break :result_block beam.make(result, .{}).v;"
+  def _default_marshal, do: []
 end
 
 defimpl Zig.Type, for: Atom do
   alias Zig.Type
 
-  def marshals_param?(_), do: false
-  def marshals_return?(_), do: false
-
-  def marshal_param(_, _, _, _), do: raise("unreachable")
-  def marshal_return(_, _, _), do: raise("unreachable")
-
   def return_allowed?(type), do: type in ~w(term erl_nif_term pid void)a
 
   def render_return(:void), do: "_ = result; break :result_block beam.make(.ok, .{}).v;"
diff --git a/lib/zig/type/bool.ex b/lib/zig/type/bool.ex
index 1e91ae55..89504f06 100644
--- a/lib/zig/type/bool.ex
+++ b/lib/zig/type/bool.ex
@@ -13,8 +13,5 @@ defmodule Zig.Type.Bool do
   def render_payload_options(type, index, _), do: Type._default_payload_options()
   def render_return(type), do: Type._default_return()
 
-  def marshals_param?(_), do: false
-  def marshals_return?(_), do: false
-
   def spec(_, _, _), do: Type.spec(:boolean)
 end
diff --git a/lib/zig/type/cpointer.ex b/lib/zig/type/cpointer.ex
index ef91434d..2889c097 100644
--- a/lib/zig/type/cpointer.ex
+++ b/lib/zig/type/cpointer.ex
@@ -24,9 +24,6 @@ defmodule Zig.Type.Cpointer do
     end
   end
 
-  def marshals_param?(_), do: false
-  def marshals_return?(_), do: false
-
   def render_payload_options(type, index, _), do: Type._default_payload_options()
   def render_return(type), do: Type._default_return()
 
diff --git a/lib/zig/type/enum.ex b/lib/zig/type/enum.ex
index 4467fa78..76ab5ef4 100644
--- a/lib/zig/type/enum.ex
+++ b/lib/zig/type/enum.ex
@@ -16,11 +16,11 @@ defmodule Zig.Type.Enum do
     ~s(%Zig.Type.Enum{name: "#{enum.name}", tags: #{Kernel.inspect(enum.tags, opts)}})
   end
 
+  
   def return_allowed?(_), do: true
-
-  def marshals_param?(_), do: false
-  def marshals_return?(_), do: false
-
+  
+  def marshal_param(_, _, _, _), do: Type._default_marshal()
+  def marshal_return(_, _, _), do: Type._default_marshal()
   def render_payload_options(type, index, _), do: Type._default_payload_options()
   def render_return(type), do: Type._default_return()
 
diff --git a/lib/zig/type/float.ex b/lib/zig/type/float.ex
index 0cce2116..16a56418 100644
--- a/lib/zig/type/float.ex
+++ b/lib/zig/type/float.ex
@@ -22,8 +22,6 @@ defmodule Zig.Type.Float do
   def spec(_, _, _), do: Type.spec(:float)
 
   def return_allowed?(_), do: true
-  def marshals_param?(_), do: false
-  def marshals_return?(_), do: false
   def render_payload_options(type, index, _), do: Type._default_payload_options()
   def render_return(type), do: Type._default_return()
 end
diff --git a/lib/zig/type/integer.ex b/lib/zig/type/integer.ex
index 90496276..2b7f92c0 100644
--- a/lib/zig/type/integer.ex
+++ b/lib/zig/type/integer.ex
@@ -51,9 +51,6 @@ defmodule Zig.Type.Integer do
     concat(["~t(", to_string(type), ")"])
   end
 
-  def marshals_param?(%{bits: bits}), do: bits > 64
-  def marshals_return?(%{bits: bits}), do: bits > 64
-
   def marshal_param(type, variable, index, :elixir) do
     marshal_param_elixir(type, variable, index)
   end
@@ -224,9 +221,6 @@ defmodule Zig.Type.Integer do
 
   def render_return(type), do: Type._default_return()
 
-  def marshals_param?(%{bits: bits}), do: bits > 64
-  def marshals_return?(%{bits: bits}), do: bits > 64
-
   def render_payload_options(type, index, _), do: Type._default_payload_options()
   def render_return(type), do: Type._default_return()
 end
diff --git a/lib/zig/type/manypointer.ex b/lib/zig/type/manypointer.ex
index 4880c5f9..98ec66ed 100644
--- a/lib/zig/type/manypointer.ex
+++ b/lib/zig/type/manypointer.ex
@@ -26,8 +26,6 @@ defmodule Zig.Type.Manypointer do
   def return_allowed?(pointer), do: pointer.has_sentinel? and Type.return_allowed?(pointer.child)
   def missing_size?(_), do: true
 
-  def marshals_param?(_), do: false
-  def marshals_return?(_), do: false
   def render_payload_options(type, index, _), do: Type._default_payload_options()
   def render_return(type), do: Type._default_return()
 
diff --git a/lib/zig/type/optional.ex b/lib/zig/type/optional.ex
index 4b00fd0e..796ec3f5 100644
--- a/lib/zig/type/optional.ex
+++ b/lib/zig/type/optional.ex
@@ -11,9 +11,6 @@ defmodule Zig.Type.Optional do
 
   def return_allowed?(optional), do: Type.return_allowed?(optional.child)
 
-  def marshals_param?(_), do: false
-  def marshals_return?(_), do: false
-
   def render_payload_options(type, index, _), do: Type._default_payload_options()
   def render_return(type), do: Type._default_return()
 
diff --git a/lib/zig/type/slice.ex b/lib/zig/type/slice.ex
index 271a7f6a..b872b676 100644
--- a/lib/zig/type/slice.ex
+++ b/lib/zig/type/slice.ex
@@ -81,8 +81,6 @@ defmodule Zig.Type.Slice do
   # ETC
 
   def return_allowed?(slice), do: Type.return_allowed?(slice.child)
-  def marshals_param?(_), do: false
-  def marshals_return?(_), do: false
   def render_payload_options(type, index, _), do: Type._default_payload_options()
   def render_return(type), do: Type._default_return()
 
diff --git a/lib/zig/type/struct.ex b/lib/zig/type/struct.ex
index 67c39311..7b6e37d9 100644
--- a/lib/zig/type/struct.ex
+++ b/lib/zig/type/struct.ex
@@ -119,8 +119,6 @@ defmodule Zig.Type.Struct do
     |> Enum.all?()
   end
 
-  def marshals_param?(_), do: false
-  def marshals_return?(_), do: false
   def render_payload_options(type, index, _), do: Type._default_payload_options()
   def render_return(type), do: Type._default_return()
 end
diff --git a/priv/beam/get.zig b/priv/beam/get.zig
index bba134d5..ec9abb21 100644
--- a/priv/beam/get.zig
+++ b/priv/beam/get.zig
@@ -726,6 +726,7 @@ inline fn error_line(msg: anytype, opts: anytype) void {
                 };
                 @compileError(error_msg);
             }
+
             opts.error_info.v = e.enif_make_list_cell(options.env(opts), beam.make(msg, opts).v, opts.error_info.v);
         }
     }
diff --git a/test/integration/types/enum_test.exs b/test/integration/types/enum_test.exs
index 05922b38..6a99f038 100644
--- a/test/integration/types/enum_test.exs
+++ b/test/integration/types/enum_test.exs
@@ -37,7 +37,7 @@ defmodule ZiglerTest.Types.EnumTest do
 
     test "if you try to use an invalid number" do
       assert_raise ArgumentError,
-                   "errors were found at the given arguments:\n\n  * 1st argument: \n\n     note: not an integer value for EnumType (should be one of `[0, 1]`)\n     expected: 0 | 1 | :foo | :bar (for `EnumType`)\n     got: `42`\n",
+                   "errors were found at the given arguments:\n\n  * 1st argument: \n\n     note: not an integer value for EnumType (should be one of `[0, 1]`)\n     expected: integer (for `u1`)\n     got: `42`\n     note: out of bounds (0..1)\n     expected: 0 | 1 | :foo | :bar (for `EnumType`)\n     got: `42`\n",
                    fn -> untagged_swap(42) end
     end
   end