diff --git a/lib/coffee-script.js b/lib/coffee-script.js
index dcd6ea73..d35ec261 100755
--- a/lib/coffee-script.js
+++ b/lib/coffee-script.js
@@ -67,8 +67,8 @@
       _ref = this.tokens[this.pos++] || [''], tag = _ref[0], this.yytext = _ref[1], this.yylineno = _ref[2];
       return tag;
     },
-    setInput: function(_arg) {
-      this.tokens = _arg;
+    setInput: function(tokens) {
+      this.tokens = tokens;
       return this.pos = 0;
     },
     upcomingInput: function() {
diff --git a/lib/nodes.js b/lib/nodes.js
index 87f6d26f..169fa89c 100644
--- a/lib/nodes.js
+++ b/lib/nodes.js
@@ -292,8 +292,8 @@
     return Expressions;
   }();
   exports.Literal = Literal = function() {
-    function Literal(_arg) {
-      this.value = _arg;
+    function Literal(value) {
+      this.value = value;
     }
     __extends(Literal, Base);
     Literal.prototype.makeReturn = function() {
@@ -327,8 +327,8 @@
     return Literal;
   }();
   exports.Return = Return = function() {
-    function Return(_arg) {
-      this.expression = _arg;
+    function Return(expression) {
+      this.expression = expression;
     }
     __extends(Return, Base);
     Return.prototype.children = ['expression'];
@@ -486,8 +486,8 @@
     return Value;
   }();
   exports.Comment = Comment = function() {
-    function Comment(_arg) {
-      this.comment = _arg;
+    function Comment(comment) {
+      this.comment = comment;
     }
     __extends(Comment, Base);
     Comment.prototype.isPureStatement = YES;
@@ -504,9 +504,9 @@
     return Comment;
   }();
   exports.Call = Call = function() {
-    function Call(variable, _arg, _arg2) {
-      this.args = _arg != null ? _arg : [];
-      this.soak = _arg2;
+    function Call(variable, args, soak) {
+      this.args = args != null ? args : [];
+      this.soak = soak;
       this.isNew = false;
       this.isSuper = variable === 'super';
       this.variable = this.isSuper ? null : variable;
@@ -632,9 +632,9 @@
     return Call;
   }();
   exports.Extends = Extends = function() {
-    function Extends(_arg, _arg2) {
-      this.child = _arg;
-      this.parent = _arg2;
+    function Extends(child, parent) {
+      this.child = child;
+      this.parent = parent;
     }
     __extends(Extends, Base);
     Extends.prototype.children = ['child', 'parent'];
@@ -645,8 +645,8 @@
     return Extends;
   }();
   exports.Access = Access = function() {
-    function Access(_arg, tag) {
-      this.name = _arg;
+    function Access(name, tag) {
+      this.name = name;
       this.proto = tag === 'proto' ? '.prototype' : '';
       this.soak = tag === 'soak';
     }
@@ -661,8 +661,8 @@
     return Access;
   }();
   exports.Index = Index = function() {
-    function Index(_arg) {
-      this.index = _arg;
+    function Index(index) {
+      this.index = index;
     }
     __extends(Index, Base);
     Index.prototype.children = ['index'];
@@ -675,9 +675,9 @@
     return Index;
   }();
   exports.Range = Range = function() {
-    function Range(_arg, _arg2, tag) {
-      this.from = _arg;
-      this.to = _arg2;
+    function Range(from, to, tag) {
+      this.from = from;
+      this.to = to;
       this.exclusive = tag === 'exclusive';
       this.equals = this.exclusive ? '' : '=';
     }
@@ -760,8 +760,8 @@
     return Range;
   }();
   exports.Slice = Slice = function() {
-    function Slice(_arg) {
-      this.range = _arg;
+    function Slice(range) {
+      this.range = range;
       Slice.__super__.constructor.call(this);
     }
     __extends(Slice, Base);
@@ -779,8 +779,8 @@
     return Slice;
   }();
   exports.Obj = Obj = function() {
-    function Obj(props, _arg) {
-      this.generated = _arg != null ? _arg : false;
+    function Obj(props, generated) {
+      this.generated = generated != null ? generated : false;
       this.objects = this.properties = props || [];
     }
     __extends(Obj, Base);
@@ -928,10 +928,10 @@
     return Arr;
   }();
   exports.Class = Class = function() {
-    function Class(_arg, _arg2, _arg3) {
-      this.variable = _arg;
-      this.parent = _arg2;
-      this.body = _arg3 != null ? _arg3 : new Expressions;
+    function Class(variable, parent, body) {
+      this.variable = variable;
+      this.parent = parent;
+      this.body = body != null ? body : new Expressions;
       this.boundFuncs = [];
     }
     __extends(Class, Base);
@@ -1057,10 +1057,10 @@
     return Class;
   }();
   exports.Assign = Assign = function() {
-    function Assign(_arg, _arg2, _arg3) {
-      this.variable = _arg;
-      this.value = _arg2;
-      this.context = _arg3;
+    function Assign(variable, value, context) {
+      this.variable = variable;
+      this.value = value;
+      this.context = context;
     }
     __extends(Assign, Base);
     Assign.prototype.METHOD_DEF = /^(?:(\S+)\.prototype\.|\S+?)?\b([$A-Za-z_][$\w]*)$/;
@@ -1313,10 +1313,10 @@
     return Code;
   }();
   exports.Param = Param = function() {
-    function Param(_arg, _arg2, _arg3) {
-      this.name = _arg;
-      this.value = _arg2;
-      this.splat = _arg3;
+    function Param(name, value, splat) {
+      this.name = name;
+      this.value = value;
+      this.splat = splat;
     }
     __extends(Param, Base);
     Param.prototype.children = ['name', 'value'];
@@ -1328,7 +1328,15 @@
       if (this.reference) {
         return this.reference;
       }
-      node = this.isComplex() ? new Literal(o.scope.freeVariable('arg')) : this.name;
+      node = this.name;
+      if (node["this"]) {
+        node = node.properties[0].name;
+        if (node.value.reserved) {
+          node = new Literal('_' + node.value);
+        }
+      } else if (node.isComplex()) {
+        node = new Literal(o.scope.freeVariable('arg'));
+      }
       node = new Value(node);
       if (this.splat) {
         node = new Splat(node);
@@ -1407,8 +1415,8 @@
       this.returns = true;
       return this;
     };
-    While.prototype.addBody = function(_arg) {
-      this.body = _arg;
+    While.prototype.addBody = function(body) {
+      this.body = body;
       return this;
     };
     While.prototype.containsPureStatement = function() {
@@ -1578,9 +1586,9 @@
     return Op;
   }();
   exports.In = In = function() {
-    function In(_arg, _arg2) {
-      this.object = _arg;
-      this.array = _arg2;
+    function In(object, array) {
+      this.object = object;
+      this.array = array;
     }
     __extends(In, Base);
     In.prototype.children = ['object', 'array'];
@@ -1632,11 +1640,11 @@
     return In;
   }();
   exports.Try = Try = function() {
-    function Try(_arg, _arg2, _arg3, _arg4) {
-      this.attempt = _arg;
-      this.error = _arg2;
-      this.recovery = _arg3;
-      this.ensure = _arg4;
+    function Try(attempt, error, recovery, ensure) {
+      this.attempt = attempt;
+      this.error = error;
+      this.recovery = recovery;
+      this.ensure = ensure;
     }
     __extends(Try, Base);
     Try.prototype.children = ['attempt', 'recovery', 'ensure'];
@@ -1660,8 +1668,8 @@
     return Try;
   }();
   exports.Throw = Throw = function() {
-    function Throw(_arg) {
-      this.expression = _arg;
+    function Throw(expression) {
+      this.expression = expression;
     }
     __extends(Throw, Base);
     Throw.prototype.children = ['expression'];
@@ -1673,8 +1681,8 @@
     return Throw;
   }();
   exports.Existence = Existence = function() {
-    function Existence(_arg) {
-      this.expression = _arg;
+    function Existence(expression) {
+      this.expression = expression;
     }
     __extends(Existence, Base);
     Existence.prototype.children = ['expression'];
@@ -1692,8 +1700,8 @@
     return Existence;
   }();
   exports.Parens = Parens = function() {
-    function Parens(_arg) {
-      this.body = _arg;
+    function Parens(body) {
+      this.body = body;
     }
     __extends(Parens, Base);
     Parens.prototype.children = ['body'];
@@ -1724,10 +1732,10 @@
     return Parens;
   }();
   exports.For = For = function() {
-    function For(body, source, _arg, _arg2) {
+    function For(body, source, name, index) {
       var _ref;
-      this.name = _arg;
-      this.index = _arg2;
+      this.name = name;
+      this.index = index;
       this.source = source.source, this.guard = source.guard, this.step = source.step;
       this.body = Expressions.wrap([body]);
       this.raw = !!source.raw;
@@ -1872,10 +1880,10 @@
     return For;
   }();
   exports.Switch = Switch = function() {
-    function Switch(_arg, _arg2, _arg3) {
-      this.subject = _arg;
-      this.cases = _arg2;
-      this.otherwise = _arg3;
+    function Switch(subject, cases, otherwise) {
+      this.subject = subject;
+      this.cases = cases;
+      this.otherwise = otherwise;
     }
     __extends(Switch, Base);
     Switch.prototype.children = ['subject', 'cases', 'otherwise'];
@@ -1933,8 +1941,8 @@
     return Switch;
   }();
   exports.If = If = function() {
-    function If(condition, _arg, options) {
-      this.body = _arg;
+    function If(condition, body, options) {
+      this.body = body;
       options == null && (options = {});
       this.condition = options.invert ? condition.invert() : condition;
       this.elseBody = null;
diff --git a/lib/optparse.js b/lib/optparse.js
index a2ab4237..43ab8ea7 100755
--- a/lib/optparse.js
+++ b/lib/optparse.js
@@ -1,8 +1,8 @@
 (function() {
   var LONG_FLAG, MULTI_FLAG, OPTIONAL, OptionParser, SHORT_FLAG, buildRule, buildRules, normalizeArguments;
   exports.OptionParser = OptionParser = function() {
-    function OptionParser(rules, _arg) {
-      this.banner = _arg;
+    function OptionParser(rules, banner) {
+      this.banner = banner;
       this.rules = buildRules(rules);
     }
     OptionParser.prototype.parse = function(args) {
diff --git a/lib/rewriter.js b/lib/rewriter.js
index f2b27a0b..c15d5aa5 100644
--- a/lib/rewriter.js
+++ b/lib/rewriter.js
@@ -8,8 +8,8 @@
   }, __slice = Array.prototype.slice;
   exports.Rewriter = Rewriter = function() {
     function Rewriter() {}
-    Rewriter.prototype.rewrite = function(_arg) {
-      this.tokens = _arg;
+    Rewriter.prototype.rewrite = function(tokens) {
+      this.tokens = tokens;
       this.removeLeadingNewlines();
       this.removeMidExpressionNewlines();
       this.closeOpenCalls();
diff --git a/lib/scope.js b/lib/scope.js
index c07b8670..f9a1d1bf 100644
--- a/lib/scope.js
+++ b/lib/scope.js
@@ -2,10 +2,10 @@
   var Scope, extend, last, _ref;
   _ref = require('./helpers'), extend = _ref.extend, last = _ref.last;
   exports.Scope = Scope = function() {
-    function Scope(_arg, _arg2, _arg3) {
-      this.parent = _arg;
-      this.expressions = _arg2;
-      this.method = _arg3;
+    function Scope(parent, expressions, method) {
+      this.parent = parent;
+      this.expressions = expressions;
+      this.method = method;
       this.variables = [
         {
           name: 'arguments',
diff --git a/src/nodes.coffee b/src/nodes.coffee
index 3588b519..eee4b4f4 100644
--- a/src/nodes.coffee
+++ b/src/nodes.coffee
@@ -1056,7 +1056,12 @@ exports.Param = class Param extends Base
 
   asReference: (o) ->
     return @reference if @reference
-    node = if @isComplex() then new Literal o.scope.freeVariable 'arg' else @name
+    node = @name
+    if node.this
+      node = node.properties[0].name
+      node = new Literal '_' + node.value if node.value.reserved
+    else if node.isComplex()
+      node = new Literal o.scope.freeVariable 'arg'
     node = new Value node
     node = new Splat node if @splat
     @reference = node