diff --git a/lib/execjs/support/node_runner.js b/lib/execjs/support/node_runner.js
index 3dc4757..2987d9f 100644
--- a/lib/execjs/support/node_runner.js
+++ b/lib/execjs/support/node_runner.js
@@ -4,7 +4,17 @@
     process.stdout.write('' + string);
   };
   try {
+    var __process__ = process;
+    delete this.process;
+    delete this.console;
+    delete this.setTimeout;
+    delete this.setInterval;
+    delete this.clearTimeout;
+    delete this.clearInterval;
+    delete this.setImmediate;
+    delete this.clearImmediate;
     result = program();
+    this.process = __process__;
     if (typeof result == 'undefined' && result !== null) {
       print('["ok"]');
     } else {
@@ -15,6 +25,7 @@
       }
     }
   } catch (err) {
+    this.process = __process__;
     print(JSON.stringify(['err', '' + err, err.stack]));
   }
 });
diff --git a/test/test_execjs.rb b/test/test_execjs.rb
index 061be48..0ee411f 100644
--- a/test/test_execjs.rb
+++ b/test/test_execjs.rb
@@ -239,16 +239,22 @@ class TestExecJS < Test
 
   def test_node_process_is_undefined
     assert ExecJS.eval("typeof process == 'undefined'")
+    refute ExecJS.eval("'process' in this")
   end
 
   def test_commonjs_vars_are_undefined
     assert ExecJS.eval("typeof module == 'undefined'")
     assert ExecJS.eval("typeof exports == 'undefined'")
     assert ExecJS.eval("typeof require == 'undefined'")
+
+    refute ExecJS.eval("'module' in this")
+    refute ExecJS.eval("'exports' in this")
+    refute ExecJS.eval("'require' in this")
   end
 
   def test_console_is_undefined
     assert ExecJS.eval("typeof console == 'undefined'")
+    refute ExecJS.eval("'console' in this")
   end
 
   def test_timers_are_undefined
@@ -258,6 +264,13 @@ class TestExecJS < Test
     assert ExecJS.eval("typeof clearInterval == 'undefined'")
     assert ExecJS.eval("typeof setImmediate == 'undefined'")
     assert ExecJS.eval("typeof clearImmediate == 'undefined'")
+
+    refute ExecJS.eval("'setTimeout' in this")
+    refute ExecJS.eval("'setInterval' in this")
+    refute ExecJS.eval("'clearTimeout' in this")
+    refute ExecJS.eval("'clearInterval' in this")
+    refute ExecJS.eval("'setImmediate' in this")
+    refute ExecJS.eval("'clearImmediate' in this")
   end
 
   def test_compile_large_scripts