diff --git a/bin/moonc b/bin/moonc
index d7a9220..ed7f527 100755
--- a/bin/moonc
+++ b/bin/moonc
@@ -9,8 +9,8 @@ local dump_tree = require"moonscript.dump".tree
 local alt_getopt = require "alt_getopt"
 local lfs = require "lfs"
 
-local opts, ind = alt_getopt.get_opts(arg, "vhwt:pTXb", {
-	print = "p", tree = "T", version = "v", help = "h"
+local opts, ind = alt_getopt.get_opts(arg, "lvhwt:pTXb", {
+	print = "p", tree = "T", version = "v", help = "h", lint = "l"
 })
 
 local read_stdin = arg[1] == "--"
@@ -25,6 +25,7 @@ local help = [[Usage: %s [options] files...
     -p          Write output to standard out
     -T          Write parse tree instead of code (to stdout)
     -X          Write line rewrite map instead of code (to stdout)
+    -l          Perform lint on the file instead of compiling
     -b          Dump parse and compile time (doesn't write output)
     -v          Print version
 
@@ -377,6 +378,15 @@ if opts.w then
 	end
 
 	print "\nQuitting..."
+elseif opts.l then
+	for _, fname in pairs(files) do
+		lint = require "moonscript.cmd.lint"
+		local res = lint.lint_file(fname)
+		if res then
+			print(res)
+			print()
+		end
+	end
 else
 	for _, fname in ipairs(files) do
 		local success, err = compile_and_write(fname, target_dir..convert_path(fname))
diff --git a/moonscript/cmd/lint.lua b/moonscript/cmd/lint.lua
new file mode 100644
index 0000000..24e144a
--- /dev/null
+++ b/moonscript/cmd/lint.lua
@@ -0,0 +1,145 @@
+local insert
+do
+  local _obj_0 = table
+  insert = _obj_0.insert
+end
+local Set
+do
+  local _obj_0 = require("moonscript.data")
+  Set = _obj_0.Set
+end
+local Block
+do
+  local _obj_0 = require("moonscript.compile")
+  Block = _obj_0.Block
+end
+local whitelist_globals = Set({
+  "print"
+})
+local LinterBlock
+do
+  local _parent_0 = Block
+  local _base_0 = {
+    block = function(self, ...)
+      do
+        local _with_0 = _parent_0.block(self, ...)
+        _with_0.value_compilers = self.value_compilers
+        return _with_0
+      end
+    end
+  }
+  _base_0.__index = _base_0
+  setmetatable(_base_0, _parent_0.__base)
+  local _class_0 = setmetatable({
+    __init = function(self, lint_errors, ...)
+      if lint_errors == nil then
+        lint_errors = { }
+      end
+      self.lint_errors = lint_errors
+      _parent_0.__init(self, ...)
+      local vc = self.value_compilers
+      self.value_compilers = setmetatable({
+        raw_value = function(block, name)
+          if name:match("^[%w_]+$") and not block:has_name(name) and not whitelist_globals[name] then
+            local stm = block.current_stms[block.current_stm_i]
+            insert(self.lint_errors, {
+              "accessing global " .. tostring(name),
+              stm[-1]
+            })
+          end
+          return vc.raw_value(block, name)
+        end
+      }, {
+        __index = vc
+      })
+    end,
+    __base = _base_0,
+    __name = "LinterBlock",
+    __parent = _parent_0
+  }, {
+    __index = function(cls, name)
+      local val = rawget(_base_0, name)
+      if val == nil then
+        return _parent_0[name]
+      else
+        return val
+      end
+    end,
+    __call = function(cls, ...)
+      local _self_0 = setmetatable({}, _base_0)
+      cls.__init(_self_0, ...)
+      return _self_0
+    end
+  })
+  _base_0.__class = _class_0
+  if _parent_0.__inherited then
+    _parent_0.__inherited(_parent_0, _class_0)
+  end
+  LinterBlock = _class_0
+end
+local format_lint
+format_lint = function(errors, code, header)
+  if not (next(errors)) then
+    return 
+  end
+  local pos_to_line, get_line
+  do
+    local _obj_0 = require("moonscript.util")
+    pos_to_line, get_line = _obj_0.pos_to_line, _obj_0.get_line
+  end
+  local formatted
+  do
+    local _accum_0 = { }
+    local _len_0 = 1
+    for _index_0 = 1, #errors do
+      local _des_0 = errors[_index_0]
+      local msg, pos
+      msg, pos = _des_0[1], _des_0[2]
+      if pos then
+        local line = pos_to_line(code, pos)
+        msg = "line " .. tostring(line) .. ": " .. tostring(msg)
+        local line_text = "> " .. get_line(code, line)
+        local sep_len = math.max(#msg, #line_text)
+        _accum_0[_len_0] = table.concat({
+          msg,
+          ("="):rep(sep_len),
+          line_text
+        }, "\n")
+      else
+        _accum_0[_len_0] = msg
+      end
+      _len_0 = _len_0 + 1
+    end
+    formatted = _accum_0
+  end
+  if header then
+    table.insert(formatted, 1, header)
+  end
+  return table.concat(formatted, "\n\n")
+end
+local lint_code
+lint_code = function(code, name)
+  if name == nil then
+    name = "string input"
+  end
+  local parse = require("moonscript.parse")
+  local tree, err = parse.string(code)
+  if not (tree) then
+    return nil, err
+  end
+  local scope = LinterBlock()
+  scope:stms(tree)
+  return format_lint(scope.lint_errors, code, name)
+end
+local lint_file
+lint_file = function(fname)
+  local f, err = io.open(fname)
+  if not (f) then
+    return nil, err
+  end
+  return lint_code(f:read("*a"), fname)
+end
+return {
+  lint_code = lint_code,
+  lint_file = lint_file
+}
diff --git a/moonscript/cmd/lint.moon b/moonscript/cmd/lint.moon
new file mode 100644
index 0000000..dd3568d
--- /dev/null
+++ b/moonscript/cmd/lint.moon
@@ -0,0 +1,72 @@
+
+import insert from table
+import Set from require "moonscript.data"
+import Block from require "moonscript.compile"
+
+-- globals allowed to be referenced
+whitelist_globals = Set {
+  "print"
+}
+
+class LinterBlock extends Block
+  new: (@lint_errors={}, ...) =>
+    super ...
+
+    vc = @value_compilers
+    @value_compilers = setmetatable {
+      raw_value: (block, name) ->
+
+        if name\match("^[%w_]+$") and not block\has_name(name) and not whitelist_globals[name]
+          stm = block.current_stms[block.current_stm_i]
+          insert @lint_errors, {
+            "accessing global #{name}"
+            stm[-1]
+          }
+
+        vc.raw_value block, name
+    }, __index: vc
+
+  block: (...) =>
+    with super ...
+      .value_compilers = @value_compilers
+
+format_lint = (errors, code, header) ->
+  return unless next errors
+
+  import pos_to_line, get_line from require "moonscript.util"
+  formatted = for {msg, pos} in *errors
+    if pos
+      line = pos_to_line code, pos
+      msg = "line #{line}: #{msg}"
+      line_text = "> " .. get_line code, line
+
+      sep_len = math.max #msg, #line_text
+      table.concat {
+        msg
+        "="\rep sep_len
+        line_text
+      }, "\n"
+
+    else
+      msg
+
+  table.insert formatted, 1, header if header
+  table.concat formatted, "\n\n"
+
+
+lint_code = (code, name="string input") ->
+  parse = require "moonscript.parse"
+  tree, err = parse.string code
+  return nil, err unless tree
+
+  scope = LinterBlock!
+  scope\stms tree
+  format_lint scope.lint_errors, code, name
+
+lint_file = (fname) ->
+  f, err = io.open fname
+  return nil, err unless f
+  lint_code f\read("*a"), fname
+
+
+{ :lint_code, :lint_file }
diff --git a/moonscript/compile.lua b/moonscript/compile.lua
index 83f95cd..0970eab 100644
--- a/moonscript/compile.lua
+++ b/moonscript/compile.lua
@@ -271,6 +271,7 @@ do
     footer = "end",
     export_all = false,
     export_proper = false,
+    value_compilers = value_compilers,
     __tostring = function(self)
       local h
       if "string" == type(self.header) then
@@ -459,7 +460,7 @@ do
     end,
     is_value = function(self, node)
       local t = ntype(node)
-      return value_compilers[t] ~= nil or t == "value"
+      return self.value_compilers[t] ~= nil or t == "value"
     end,
     name = function(self, node, ...)
       return self:value(node, ...)
@@ -472,7 +473,7 @@ do
       else
         action = node[1]
       end
-      local fn = value_compilers[action]
+      local fn = self.value_compilers[action]
       if not fn then
         error("Failed to compile value: " .. dump.value(node))
       end
diff --git a/moonscript/compile.moon b/moonscript/compile.moon
index 0d99946..33bb719 100644
--- a/moonscript/compile.moon
+++ b/moonscript/compile.moon
@@ -161,6 +161,8 @@ class Block
   export_all: false
   export_proper: false
 
+  value_compilers: value_compilers
+
   __tostring: =>
     h = if "string" == type @header
       @header
@@ -316,7 +318,7 @@ class Block
 
   is_value: (node) =>
     t = ntype node
-    value_compilers[t] != nil or t == "value"
+    @value_compilers[t] != nil or t == "value"
 
   -- line wise compile functions
   name: (node, ...) => @value node, ...
@@ -328,7 +330,7 @@ class Block
     else
       node[1]
 
-    fn = value_compilers[action]
+    fn = @value_compilers[action]
     error "Failed to compile value: "..dump.value node if not fn
 
     out = fn self, node, ...