diff --git a/lib/compress.js b/lib/compress.js
index e135acaf..ba7c10f4 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -3530,6 +3530,7 @@ merge(Compressor.prototype, {
                 && !exp.uses_arguments
                 && !exp.uses_eval
                 && exp.body.length == 1
+                && !exp.contains_this()
                 && all(exp.argnames, function(arg) {
                     return arg.__unused;
                 })
@@ -3543,23 +3544,6 @@ merge(Compressor.prototype, {
                         expression: stat.body
                     });
                 }
-                if (value) {
-                    var tw = new TreeWalker(function(node) {
-                        if (!value) return true;
-                        if (node instanceof AST_SymbolRef) {
-                            var ref = node.scope.find_variable(node);
-                            if (ref && ref.scope.parent_scope === fn.parent_scope) {
-                                value = null;
-                                return true;
-                            }
-                        }
-                        if (node instanceof AST_This && !tw.find_parent(AST_Scope)) {
-                            value = null;
-                            return true;
-                        }
-                    });
-                    value.walk(tw);
-                }
                 if (value) {
                     var args = self.args.concat(value);
                     return make_sequence(self, args).optimize(compressor);