diff --git a/Lib/runpy.py b/Lib/runpy.py
index 8096aac..d2f18d3 100755
--- a/Lib/runpy.py
+++ b/Lib/runpy.py
@@ -33,21 +33,36 @@
     return run_globals
 
 def _run_module_code(code, init_globals=None,
-                     mod_name=None, mod_fname=None,
-                     mod_loader=None, alter_sys=False):
+                    mod_name=None, mod_fname=None,
+                    mod_loader=None, alter_sys=False):
     """Helper for run_module"""
     # Set up the top level namespace dictionary
     if alter_sys:
-        # Modify sys.argv[0] and sys.modules[mod_name]
+        # Modify sys.argv[0] and sys.module[mod_name]
+        temp_module = imp.new_module(mod_name)
+        mod_globals = temp_module.__dict__
+        saved_argv0 = sys.argv[0]
+        restore_module = mod_name in sys.modules
+        if restore_module:
+            saved_module = sys.modules[mod_name]
         sys.argv[0] = mod_fname
-        module = imp.new_module(mod_name)
-        sys.modules[mod_name] = module
-        mod_globals = module.__dict__
+        sys.modules[mod_name] = temp_module
+        try:
+            _run_code(code, mod_globals, init_globals,
+                      mod_name, mod_fname, mod_loader)
+        finally:
+            sys.argv[0] = saved_argv0
+        if restore_module:
+            sys.modules[mod_name] = saved_module
+        else:
+            del sys.modules[mod_name]
+        # Copy the globals of the temporary module, as they
+        # may be cleared when the temporary module goes away
+        return mod_globals.copy()
     else:
         # Leave the sys module alone
-        mod_globals = {}
-    return _run_code(code, mod_globals, init_globals,
-                     mod_name, mod_fname, mod_loader)
+        return _run_code(code, {}, init_globals,
+                         mod_name, mod_fname, mod_loader)
 
 
 # This helper is needed due to a missing component in the PEP 302
diff --git a/Lib/test/test_runpy.py b/Lib/test/test_runpy.py
index 7076df7..9de9811 100644
--- a/Lib/test/test_runpy.py
+++ b/Lib/test/test_runpy.py
@@ -26,7 +26,8 @@
         "   module_in_sys_modules = globals() is sys.modules[__name__].__dict__\n"
         "# Check nested operation\n"
         "import runpy\n"
-        "nested = runpy._run_module_code('x=1\\n', mod_name='<run>')\n"
+        "nested = runpy._run_module_code('x=1\\n', mod_name='<run>',\n"
+        "                                          alter_sys=True)\n"
     )
 
 
@@ -37,44 +38,35 @@
         loader = "Now you're just being silly"
         d1 = dict(initial=initial)
         saved_argv0 = sys.argv[0]
-        try:
-            d2 = _run_module_code(self.test_source,
-                                d1,
-                                name,
-                                file,
-                                loader,
-                                alter_sys=True)
-            self.failUnless("result" not in d1)
-            self.failUnless(d2["initial"] is initial)
-            self.failUnless(d2["result"] == self.expected_result)
-            self.failUnless(d2["nested"]["x"] == 1)
-            self.failUnless(d2["nested"]["__name__"] == "<run>")
-            self.failUnless(d2["__name__"] is name)
-            self.failUnless(d2["__file__"] is file)
-            self.failUnless(d2["__loader__"] is loader)
-            self.failUnless(d2["run_argv0"] is file)
-            self.failUnless(d2["run_name_in_sys_modules"])
-            self.failUnless(d2["module_in_sys_modules"])
-            self.failUnless(sys.argv[0] is not saved_argv0)
-            self.failUnless(name in sys.modules)
-        finally:
-            sys.argv[0] = saved_argv0
-            if name in sys.modules:
-                del sys.modules[name]
+        d2 = _run_module_code(self.test_source,
+                              d1,
+                              name,
+                              file,
+                              loader,
+                              True)
+        self.failUnless("result" not in d1)
+        self.failUnless(d2["initial"] is initial)
+        self.failUnless(d2["result"] == self.expected_result)
+        self.failUnless(d2["nested"]["x"] == 1)
+        self.failUnless(d2["__name__"] is name)
+        self.failUnless(d2["run_name_in_sys_modules"])
+        self.failUnless(d2["module_in_sys_modules"])
+        self.failUnless(d2["__file__"] is file)
+        self.failUnless(d2["run_argv0"] is file)
+        self.failUnless(d2["__loader__"] is loader)
+        self.failUnless(sys.argv[0] is saved_argv0)
+        self.failUnless(name not in sys.modules)
 
     def test_run_module_code_defaults(self):
         saved_argv0 = sys.argv[0]
         d = _run_module_code(self.test_source)
         self.failUnless(d["result"] == self.expected_result)
-        self.failUnless(d["nested"]["x"] == 1)
-        self.failUnless(d["nested"]["__name__"] == "<run>")
         self.failUnless(d["__name__"] is None)
         self.failUnless(d["__file__"] is None)
         self.failUnless(d["__loader__"] is None)
         self.failUnless(d["run_argv0"] is saved_argv0)
-        self.failUnless(not d["run_name_in_sys_modules"])
+        self.failUnless("run_name" not in d)
         self.failUnless(sys.argv[0] is saved_argv0)
-        self.failUnless(None not in sys.modules)
 
 class RunModuleTest(unittest.TestCase):