diff --git a/py/plugin/pytest_genscript.py b/py/plugin/pytest_genscript.py
index c25ade1bf..468b71117 100755
--- a/py/plugin/pytest_genscript.py
+++ b/py/plugin/pytest_genscript.py
@@ -40,7 +40,7 @@ def main(pybasedir, outfile, infile):
 
     name2src = {}
     for f in files:
-        k = f.replace("/", ".")[:-3]
+        k = f.replace(os.sep, ".")[:-3]
         name2src[k] = open(f, "rb").read()
 
     data = pickle.dumps(name2src, 2)
diff --git a/py/plugin/pytest_pytester.py b/py/plugin/pytest_pytester.py
index 89cfd38ce..abe2ebb9a 100644
--- a/py/plugin/pytest_pytester.py
+++ b/py/plugin/pytest_pytester.py
@@ -69,8 +69,8 @@ class TmpTestdir:
         self.tmpdir = tmpdir.mkdir(name)
         self.plugins = []
         self._syspathremove = []
-        self.chdir() # always chdir
-        assert hasattr(self, '_olddir')
+        if not hasattr(request.function, "nochdir"):
+            self.chdir() # always chdir
         self.request.addfinalizer(self.finalize)
 
     def __repr__(self):
@@ -280,12 +280,7 @@ class TmpTestdir:
         return py.std.subprocess.Popen(cmdargs, stdout=stdout, stderr=stderr, **kw)
 
     def run(self, *cmdargs):
-        old = self.tmpdir.chdir()
-        #print "chdir", self.tmpdir
-        try:
-            return self._run(*cmdargs)
-        finally:
-            old.chdir()
+        return self._run(*cmdargs)
 
     def _run(self, *cmdargs):
         cmdargs = [str(x) for x in cmdargs]
diff --git a/testing/plugin/test_pytest_genscript.py b/testing/plugin/test_pytest_genscript.py
index ecf6d8023..76b1c6c90 100644
--- a/testing/plugin/test_pytest_genscript.py
+++ b/testing/plugin/test_pytest_genscript.py
@@ -4,11 +4,15 @@ import subprocess
 def pytest_funcarg__standalone(request):
     return request.cached_setup(scope="module", setup=lambda: Standalone(request))
 
+pytestmark = py.test.mark.nochdir
+
 class Standalone:
     def __init__(self, request):
         self.testdir = request.getfuncargvalue("testdir")
         self.script = self.testdir.tmpdir.join("mypytest")
-        self.testdir.runpytest("--genscript=%s" % self.script)
+        result = self.testdir.runpytest("--genscript=%s" % self.script)
+        assert result.ret == 0
+        assert self.script.check()
 
     def run(self, anypython, testdir, *args):
         testdir.chdir()