diff --git a/lib/coffeescript/browser.js b/lib/coffeescript/browser.js
index 757595c8..e950db84 100644
--- a/lib/coffeescript/browser.js
+++ b/lib/coffeescript/browser.js
@@ -9,7 +9,7 @@
 
   compile = CoffeeScript.compile;
 
-  CoffeeScript["eval"] = function(code, options = {}) {
+  CoffeeScript.eval = function(code, options = {}) {
     if (options.bare == null) {
       options.bare = true;
     }
diff --git a/lib/coffeescript/cake.js b/lib/coffeescript/cake.js
index 0efc6a7a..5ae03160 100644
--- a/lib/coffeescript/cake.js
+++ b/lib/coffeescript/cake.js
@@ -58,7 +58,7 @@
       e = error;
       return fatalError(`${e}`);
     }
-    ref = options["arguments"];
+    ref = options.arguments;
     results = [];
     for (i = 0, len = ref.length; i < len; i++) {
       arg = ref[i];
diff --git a/lib/coffeescript/coffeescript.js b/lib/coffeescript/coffeescript.js
index 02da4f06..20521183 100644
--- a/lib/coffeescript/coffeescript.js
+++ b/lib/coffeescript/coffeescript.js
@@ -167,7 +167,7 @@
     return mainModule._compile(code, mainModule.filename);
   };
 
-  exports["eval"] = function(code, options = {}) {
+  exports.eval = function(code, options = {}) {
     var Module, _module, _require, createContext, i, isContext, js, k, len, o, r, ref, ref1, ref2, ref3, sandbox, v;
     if (!(code = code.trim())) {
       return;
diff --git a/lib/coffeescript/command.js b/lib/coffeescript/command.js
index acd38041..350d3269 100644
--- a/lib/coffeescript/command.js
+++ b/lib/coffeescript/command.js
@@ -74,13 +74,13 @@
     if (opts.stdio) {
       return compileStdio();
     }
-    if (opts["eval"]) {
-      return compileScript(null, opts["arguments"][0]);
+    if (opts.eval) {
+      return compileScript(null, opts.arguments[0]);
     }
-    if (!opts["arguments"].length) {
+    if (!opts.arguments.length) {
       return require('./repl').start(replCliOpts);
     }
-    literals = opts.run ? opts["arguments"].splice(1) : [];
+    literals = opts.run ? opts.arguments.splice(1) : [];
     process.argv = process.argv.slice(0, 2).concat(literals);
     process.argv[0] = 'coffee';
     if (opts.output) {
@@ -90,7 +90,7 @@
       opts.join = path.resolve(opts.join);
       console.error('\nThe --join option is deprecated and will be removed in a future version.\n\nIf for some reason it\'s necessary to share local variables between files,\nreplace...\n\n    $ coffee --compile --join bundle.js -- a.coffee b.coffee c.coffee\n\nwith...\n\n    $ cat a.coffee b.coffee c.coffee | coffee --compile --stdio > bundle.js\n');
     }
-    ref = opts["arguments"];
+    ref = opts.arguments;
     results = [];
     for (i = 0, len = ref.length; i < len; i++) {
       source = ref[i];
@@ -212,7 +212,7 @@
       } else if (o.run) {
         CoffeeScript.register();
         if (opts.prelude) {
-          CoffeeScript["eval"](opts.prelude, t.options);
+          CoffeeScript.eval(opts.prelude, t.options);
         }
         return CoffeeScript.run(t.input, t.options);
       } else if (o.join && t.file !== o.join) {
@@ -536,7 +536,7 @@
     o = opts = optionParser.parse(process.argv.slice(2));
     o.compile || (o.compile = !!o.output);
     o.run = !(o.compile || o.print || o.map);
-    return o.print = !!(o.print || (o["eval"] || o.stdio && o.compile));
+    return o.print = !!(o.print || (o.eval || o.stdio && o.compile));
   };
 
   compileOptions = function(filename, base) {
diff --git a/lib/coffeescript/nodes.js b/lib/coffeescript/nodes.js
index 7cf2535a..aac38398 100644
--- a/lib/coffeescript/nodes.js
+++ b/lib/coffeescript/nodes.js
@@ -926,7 +926,7 @@
 
       looksStatic(className) {
         var ref1;
-        return (this["this"] || this.base instanceof ThisLiteral || this.base.value === className) && this.properties.length === 1 && ((ref1 = this.properties[0].name) != null ? ref1.value : void 0) !== 'prototype';
+        return (this.this || this.base instanceof ThisLiteral || this.base.value === className) && this.properties.length === 1 && ((ref1 = this.properties[0].name) != null ? ref1.value : void 0) !== 'prototype';
       }
 
       unwrap() {
@@ -1289,15 +1289,11 @@
       }
 
       compileToFragments(o) {
-        var name, node, ref1;
+        var name, node;
         name = this.name.compileToFragments(o);
         node = this.name.unwrap();
         if (node instanceof PropertyName) {
-          if (ref1 = node.value, indexOf.call(JS_FORBIDDEN, ref1) >= 0) {
-            return [this.makeCode('["'), ...name, this.makeCode('"]')];
-          } else {
-            return [this.makeCode('.'), ...name];
-          }
+          return [this.makeCode('.'), ...name];
         } else {
           return [this.makeCode('['), ...name, this.makeCode(']')];
         }
@@ -1529,7 +1525,7 @@
           indent = isCompact || prop instanceof Comment ? '' : idt;
           key = prop instanceof Assign && prop.context === 'object' ? prop.variable : prop instanceof Assign ? (!this.lhs ? prop.operatorToken.error(`unexpected ${prop.operatorToken.value}`) : void 0, prop.variable) : !(prop instanceof Comment) ? prop : void 0;
           if (key instanceof Value && key.hasProperties()) {
-            if (prop.context === 'object' || !key["this"]) {
+            if (prop.context === 'object' || !key.this) {
               key.error('invalid object key');
             }
             key = key.properties[0].name;
@@ -1965,7 +1961,7 @@
     class ExecutableClassBody extends Base {
       constructor(_class, body1 = new Block) {
         super();
-        this["class"] = _class;
+        this.class = _class;
         this.body = body1;
       }
 
@@ -1977,7 +1973,7 @@
         if (argumentsNode = this.body.contains(isLiteralArguments)) {
           argumentsNode.error("Class bodies shouldn't reference arguments");
         }
-        this.name = (ref1 = this["class"].name) != null ? ref1 : this.defaultClassVariableName;
+        this.name = (ref1 = this.class.name) != null ? ref1 : this.defaultClassVariableName;
         directives = this.walkBody();
         this.setContext();
         ident = new IdentifierLiteral(this.name);
@@ -1987,23 +1983,23 @@
         klass = new Parens(new Call(wrapper, args));
         this.body.spaced = true;
         o.classScope = wrapper.makeScope(o.scope);
-        if (this["class"].hasNameClash) {
+        if (this.class.hasNameClash) {
           parent = new IdentifierLiteral(o.classScope.freeVariable('superClass'));
           wrapper.params.push(new Param(parent));
-          args.push(this["class"].parent);
-          this["class"].parent = parent;
+          args.push(this.class.parent);
+          this.class.parent = parent;
         }
         if (this.externalCtor) {
           externalCtor = new IdentifierLiteral(o.classScope.freeVariable('ctor', {
             reserve: false
           }));
-          this["class"].externalCtor = externalCtor;
+          this.class.externalCtor = externalCtor;
           this.externalCtor.variable.base = externalCtor;
         }
-        if (this.name !== this["class"].name) {
-          this.body.expressions.unshift(new Assign(new IdentifierLiteral(this.name), this["class"]));
+        if (this.name !== this.class.name) {
+          this.body.expressions.unshift(new Assign(new IdentifierLiteral(this.name), this.class));
         } else {
-          this.body.expressions.unshift(this["class"]);
+          this.body.expressions.unshift(this.class);
         }
         this.body.expressions.unshift(...directives);
         this.body.push(ident);
@@ -2076,7 +2072,7 @@
                 base.error('constructors must be defined at the top level of a class body');
               }
               assign = this.externalCtor = new Assign(new Value, value);
-            } else if (!assign.variable["this"]) {
+            } else if (!assign.variable.this) {
               name = new (base.shouldCache() ? Index : Access)(base);
               prototype = new Access(new PropertyName('prototype'));
               variable = new Value(new ThisLiteral(), [prototype, name]);
@@ -2360,7 +2356,7 @@
       }
 
       compileNode(o) {
-        var answer, compiledName, isValue, j, name, properties, prototype, ref1, ref2, ref3, ref4, ref5, ref6, val, varBase;
+        var answer, compiledName, isValue, j, name, properties, prototype, ref1, ref2, ref3, ref4, ref5, val, varBase;
         isValue = this.variable instanceof Value;
         if (isValue) {
           this.variable.param = this.param;
@@ -2418,9 +2414,6 @@
           if (this.variable.shouldCache()) {
             compiledName.unshift(this.makeCode('['));
             compiledName.push(this.makeCode(']'));
-          } else if (ref6 = fragmentsToText(compiledName), indexOf.call(JS_FORBIDDEN, ref6) >= 0) {
-            compiledName.unshift(this.makeCode('"'));
-            compiledName.push(this.makeCode('"'));
           }
           return compiledName.concat(this.makeCode(": "), val);
         }
@@ -2469,7 +2462,7 @@
               defaultValue = obj.value;
               obj = obj.variable;
             }
-            idx = isObject ? obj["this"] ? obj.properties[0].name : new PropertyName(obj.unwrap().value) : new NumberLiteral(0);
+            idx = isObject ? obj.this ? obj.properties[0].name : new PropertyName(obj.unwrap().value) : new NumberLiteral(0);
           }
           acc = idx.unwrap() instanceof PropertyName;
           value = new Value(value);
@@ -2550,7 +2543,7 @@
                 defaultValue = obj.value;
                 obj = obj.variable;
               }
-              idx = isObject ? obj["this"] ? obj.properties[0].name : new PropertyName(obj.unwrap().value) : new Literal(expandedIdx || idx);
+              idx = isObject ? obj.this ? obj.properties[0].name : new PropertyName(obj.unwrap().value) : new Literal(expandedIdx || idx);
             }
             name = obj.unwrap().value;
             acc = idx.unwrap() instanceof PropertyName;
@@ -2725,7 +2718,7 @@
             node.error(`multiple parameters named '${name}'`);
           }
           paramNames.push(name);
-          if (node["this"]) {
+          if (node.this) {
             name = node.properties[0].name.value;
             if (indexOf.call(JS_FORBIDDEN, name) >= 0) {
               name = `_${name}`;
@@ -3006,7 +2999,7 @@
           return this.reference;
         }
         node = this.name;
-        if (node["this"]) {
+        if (node.this) {
           name = node.properties[0].name.value;
           if (indexOf.call(JS_FORBIDDEN, name) >= 0) {
             name = `_${name}`;
@@ -3052,7 +3045,7 @@
           } else if (obj instanceof Value) {
             if (obj.isArray() || obj.isObject()) {
               this.eachName(iterator, obj.base);
-            } else if (obj["this"]) {
+            } else if (obj.this) {
               atParam(obj);
             } else {
               iterator(obj.base.value, obj.base, this);
@@ -3072,7 +3065,7 @@
           var key;
           if (parent instanceof Obj) {
             key = node;
-            if (node["this"]) {
+            if (node.this) {
               key = node.properties[0].name;
             }
             return new Assign(new Value(key), newNode, 'object');
@@ -3235,10 +3228,10 @@
           return Op.prototype.generateDo(first);
         }
         if (op === 'new') {
-          if (first instanceof Call && !first["do"] && !first.isNew) {
+          if (first instanceof Call && !first.do && !first.isNew) {
             return first.newInstance();
           }
-          if (first instanceof Code && first.bound || first["do"]) {
+          if (first instanceof Code && first.bound || first.do) {
             first = new Parens(first);
           }
         }
@@ -3331,7 +3324,7 @@
           }
         }
         call = new Call(exp, passedParams);
-        call["do"] = true;
+        call.do = true;
         return call;
       }
 
diff --git a/lib/coffeescript/optparse.js b/lib/coffeescript/optparse.js
index f7ab8f77..3cc639ff 100644
--- a/lib/coffeescript/optparse.js
+++ b/lib/coffeescript/optparse.js
@@ -13,7 +13,7 @@
     parse(args) {
       var arg, i, isOption, j, k, len, len1, matchedRule, options, originalArgs, pos, ref, rule, seenNonOptionArg, skippingArgument, value;
       options = {
-        "arguments": []
+        arguments: []
       };
       skippingArgument = false;
       originalArgs = args;
@@ -26,11 +26,11 @@
         }
         if (arg === '--') {
           pos = originalArgs.indexOf('--');
-          options["arguments"] = options["arguments"].concat(originalArgs.slice(pos + 1));
+          options.arguments = options.arguments.concat(originalArgs.slice(pos + 1));
           break;
         }
         isOption = !!(arg.match(LONG_FLAG) || arg.match(SHORT_FLAG));
-        seenNonOptionArg = options["arguments"].length > 0;
+        seenNonOptionArg = options.arguments.length > 0;
         if (!seenNonOptionArg) {
           matchedRule = false;
           ref = this.rules;
@@ -52,7 +52,7 @@
           }
         }
         if (seenNonOptionArg || !isOption) {
-          options["arguments"].push(arg);
+          options.arguments.push(arg);
         }
       }
       return options;
diff --git a/lib/coffeescript/repl.js b/lib/coffeescript/repl.js
index 3db47d3a..11faae8b 100644
--- a/lib/coffeescript/repl.js
+++ b/lib/coffeescript/repl.js
@@ -24,7 +24,7 @@
       }
     })(),
     historyMaxInputSize: 10240,
-    "eval": function(input, context, filename, cb) {
+    eval: function(input, context, filename, cb) {
       var Assign, Block, Literal, Value, ast, err, js, referencedVars, token, tokens;
       input = input.replace(/\uFF00/g, '\n');
       input = input.replace(/^\(([\s\S]*)\n\)$/m, '$1');
diff --git a/src/nodes.coffee b/src/nodes.coffee
index fbfd2764..855d5337 100644
--- a/src/nodes.coffee
+++ b/src/nodes.coffee
@@ -951,10 +951,7 @@ exports.Access = class Access extends Base
     name = @name.compileToFragments o
     node = @name.unwrap()
     if node instanceof PropertyName
-      if node.value in JS_FORBIDDEN
-        [@makeCode('["'), name..., @makeCode('"]')]
-      else
-        [@makeCode('.'), name...]
+      [@makeCode('.'), name...]
     else
       [@makeCode('['), name..., @makeCode(']')]
 
@@ -1781,9 +1778,6 @@ exports.Assign = class Assign extends Base
       if @variable.shouldCache()
         compiledName.unshift @makeCode '['
         compiledName.push @makeCode ']'
-      else if fragmentsToText(compiledName) in JS_FORBIDDEN
-        compiledName.unshift @makeCode '"'
-        compiledName.push @makeCode '"'
       return compiledName.concat @makeCode(": "), val
 
     answer = compiledName.concat @makeCode(" #{ @context or '=' } "), val
diff --git a/test/modules.coffee b/test/modules.coffee
index bf9f7527..0fd8f780 100644
--- a/test/modules.coffee
+++ b/test/modules.coffee
@@ -770,7 +770,7 @@ test "#4451: `default` in an export statement is only treated as a keyword when
   input = "export default { default: 1 }"
   output = """
     export default {
-      "default": 1
+      default: 1
     };
   """
   eq toJS(input), output