diff --git a/bin/uglifyjs b/bin/uglifyjs
index 88fd46bd..8a510d61 100755
--- a/bin/uglifyjs
+++ b/bin/uglifyjs
@@ -122,6 +122,10 @@ if (MANGLE && ARGS.r) {
     MANGLE.except = ARGS.r.replace(/^\s+|\s+$/g).split(/\s*,+\s*/);
 }
 
+if (MANGLE && ARGS.screw_ie) {
+    MANGLE.screw_ie = true;
+}
+
 var OUTPUT_OPTIONS = {
     beautify: BEAUTIFY ? true : false
 };
diff --git a/lib/parse.js b/lib/parse.js
index 5a75e753..dba87023 100644
--- a/lib/parse.js
+++ b/lib/parse.js
@@ -149,7 +149,7 @@ function is_unicode_connector_punctuation(ch) {
 };
 
 function is_identifier(name) {
-    return /^[a-z_$][a-z0-9_$]*$/i.test(name) && !RESERVED_WORDS(name);
+    return !RESERVED_WORDS(name) && /^[a-z_$][a-z0-9_$]*$/i.test(name);
 };
 
 function is_identifier_start(code) {
diff --git a/lib/scope.js b/lib/scope.js
index c6a85592..503c1890 100644
--- a/lib/scope.js
+++ b/lib/scope.js
@@ -62,15 +62,16 @@ SymbolDef.prototype = {
             || (!(options && options.eval) && (this.scope.uses_eval || this.scope.uses_with));
     },
     mangle: function(options) {
-        if (!this.mangled_name && !this.unmangleable(options))
-            this.mangled_name = this.scope.next_mangled(options);
+        if (!this.mangled_name && !this.unmangleable(options)) {
+            var s = this.scope;
+            if (this.orig[0] instanceof AST_SymbolLambda && !options.screw_ie)
+                s = s.parent_scope;
+            this.mangled_name = s.next_mangled(options);
+        }
     }
 };
 
-AST_Toplevel.DEFMETHOD("figure_out_scope", function(options){
-    options = defaults(options, {
-        screw_ie: false
-    });
+AST_Toplevel.DEFMETHOD("figure_out_scope", function(){
     // This does what ast_add_scope did in UglifyJS v1.
     //
     // Part of it could be done at parse time, but it would complicate
@@ -124,15 +125,7 @@ AST_Toplevel.DEFMETHOD("figure_out_scope", function(options){
             node.init_scope_vars();
         }
         if (node instanceof AST_SymbolLambda) {
-            if (options.screw_ie) {
-                scope.def_function(node);
-            } else {
-                // https://github.com/mishoo/UglifyJS2/issues/24 — MSIE
-                // leaks function expression names into the containing
-                // scope.  Don't like this fix but seems we can't do any
-                // better.  IE: please die. Please!
-                (node.scope = scope.parent_scope).def_function(node);
-            }
+            scope.def_function(node);
         }
         else if (node instanceof AST_SymbolDefun) {
             // Careful here, the scope where this should be defined is
@@ -284,14 +277,14 @@ AST_Scope.DEFMETHOD("def_variable", function(symbol){
 });
 
 AST_Scope.DEFMETHOD("next_mangled", function(options){
-    var ext = this.enclosed, n = ext.length;
+    var ext = this.enclosed;
     out: while (true) {
         var m = base54(++this.cname);
         if (!is_identifier(m)) continue; // skip over "do"
         // we must ensure that the mangled name does not shadow a name
         // from some parent scope that is referenced in this or in
         // inner scopes.
-        for (var i = n; --i >= 0;) {
+        for (var i = ext.length; --i >= 0;) {
             var sym = ext[i];
             var name = sym.mangled_name || (sym.unmangleable(options) && sym.name);
             if (m == name) continue out;
@@ -349,7 +342,8 @@ AST_Toplevel.DEFMETHOD("_default_mangler_options", function(options){
         except   : [],
         eval     : false,
         sort     : false,
-        toplevel : false
+        toplevel : false,
+        screw_ie : false
     });
 });