diff --git a/sandbox.lua b/sandbox.lua
index be65e1c..58143f2 100644
--- a/sandbox.lua
+++ b/sandbox.lua
@@ -138,8 +138,6 @@ end
 
 -- Public interface: sandbox.protect
 function sandbox.protect(f, options)
-  if type(f) == 'string' then f = assert(loadstring(f)) end
-
   options = options or {}
 
   local quota = false
@@ -150,7 +148,11 @@ function sandbox.protect(f, options)
   local env   = merge(options.env or {}, BASE_ENV)
   env._G = env._G or env
 
-  setfenv(f, env)
+  if type(f) == 'string' then
+    f = assert(load(f, nil, options.mode, env))
+  else
+    setfenv(f, env)
+  end
 
   return function(...)
 
diff --git a/spec/sandbox_spec.lua b/spec/sandbox_spec.lua
index d1e9465..2bb04df 100644
--- a/spec/sandbox_spec.lua
+++ b/spec/sandbox_spec.lua
@@ -13,6 +13,16 @@ describe('sandbox.run', function()
       assert.equal(r, 'hello')
     end)
 
+    it('can run bytecode strings by default', function()
+      local fn = function() end
+      assert.has_no.error(function() sandbox.run(string.dump(fn)) end)
+    end)
+
+    it('can\'t run bytecode strings if given a \'t\' mode option', function()
+      local fn = function() end
+      assert.error(function() sandbox.run(string.dump(fn), { mode = 't' }) end)
+    end)
+
     it('has access to safe methods', function()
       assert.equal(10,      sandbox.run("return tonumber('10')"))
       assert.equal('HELLO', sandbox.run("return string.upper('hello')"))