diff --git a/lib/elixir_script/compiler.ex b/lib/elixir_script/compiler.ex
index f1cc9a32..ba0f869b 100644
--- a/lib/elixir_script/compiler.ex
+++ b/lib/elixir_script/compiler.ex
@@ -23,6 +23,8 @@ defmodule ElixirScript.Compiler do
     If a directory is given, file will be named `elixirscript.build.js`
 
   * `root`: Optional root for imports of FFI JavaScript modules. Defaults to `.`.
+  * `remove_unused_functions`: Removed unused functions in output. Defaults to
+    removing unused functions when Mix.env == :prod
   """
   alias ElixirScript.{
     State,
@@ -72,7 +74,9 @@ defmodule ElixirScript.Compiler do
   defp do_compile(entry_modules, pid, opts) do
     FindUsedModules.execute(entry_modules, pid)
 
-    FindUsedFunctions.execute(entry_modules, pid)
+    if opts.remove_unused_functions do
+      FindUsedFunctions.execute(entry_modules, pid)
+    end
 
     modules = State.list_modules(pid)
     Translate.execute(modules, pid)
@@ -90,6 +94,7 @@ defmodule ElixirScript.Compiler do
     |> Map.put(:output, Keyword.get(opts, :output))
     |> Map.put(:format, :es)
     |> Map.put(:root, Keyword.get(opts, :root, "."))
+    |> Map.put(:remove_unused_functions, Keyword.get(opts, :remove_unused_functions, Mix.env == :prod))
 
     options = default_options
     Map.put(options, :module_formatter, ES)
diff --git a/lib/elixir_script/passes/translate/forms/receive.ex b/lib/elixir_script/passes/translate/forms/receive.ex
index 42b76cab..1186c285 100644
--- a/lib/elixir_script/passes/translate/forms/receive.ex
+++ b/lib/elixir_script/passes/translate/forms/receive.ex
@@ -9,7 +9,7 @@ defmodule ElixirScript.Translate.Forms.Receive do
   """
   def compile(blocks, state) do
     receive_block = blocks
-    |> Keyword.get(:do)
+    |> Keyword.get(:do, [])
     |> Enum.map(fn x ->
       Clause.compile(x, state)
       |> elem(0)
diff --git a/lib/elixir_script/passes/translate/module.ex b/lib/elixir_script/passes/translate/module.ex
index 81ed418b..e39daadc 100644
--- a/lib/elixir_script/passes/translate/module.ex
+++ b/lib/elixir_script/passes/translate/module.ex
@@ -14,6 +14,10 @@ defmodule ElixirScript.Translate.Module do
     ElixirScript.Translate.Protocol.compile(module, info, pid)
   end
 
+  def compile(_module, %{attributes: [__foreign_info__: %{path: _, name: _, global: _}]}, _) do
+    nil
+  end
+
   def compile(module, info, pid) do
     %{
       attributes: attrs,
@@ -23,9 +27,10 @@ defmodule ElixirScript.Translate.Module do
       line: _line,
       module: ^module,
       unreachable: unreachable,
-      used: used
     } = info
 
+    used = Map.get(info, :used)
+
     state = %{
       module: module,
       pid: pid
@@ -39,7 +44,7 @@ defmodule ElixirScript.Translate.Module do
         _ -> true
       end)
 
-    used_defs = if Keyword.has_key?(attrs, :protocol_impl) do
+    used_defs = if Keyword.has_key?(attrs, :protocol_impl) or used == nil do
       reachable_defs
     else
       Enum.filter(reachable_defs, fn
diff --git a/lib/elixir_script/state.ex b/lib/elixir_script/state.ex
index 0946528a..7a4e03e6 100644
--- a/lib/elixir_script/state.ex
+++ b/lib/elixir_script/state.ex
@@ -51,7 +51,9 @@ defmodule ElixirScript.State do
   def has_used?(pid, module, func) do
     Agent.get(pid, fn(state) ->
       module_info = Keyword.get(state.modules, module)
-      Enum.find(module_info.used, fn(x) -> x == func end) != nil
+      used = Map.get(module_info, :used, [])
+
+      Enum.find(used, fn(x) -> x == func end) != nil
     end)
   end