diff --git a/_pytest/pytester.py b/_pytest/pytester.py
index 5442a1398..36713bf2c 100644
--- a/_pytest/pytester.py
+++ b/_pytest/pytester.py
@@ -246,8 +246,14 @@ class TmpTestdir:
         ret = None
         for name, value in items:
             p = self.tmpdir.join(name).new(ext=ext)
-            source = py.builtin._totext(py.code.Source(value)).strip()
-            content = source.encode("utf-8") # + "\n"
+            source = py.code.Source(value)
+            def my_totext(s, encoding="utf-8"):
+                if py.builtin._isbytes(s):
+                    s = py.builtin._totext(s, encoding=encoding)
+                return s
+            source_unicode = "\n".join([my_totext(line) for line in source.lines])
+            source = py.builtin._totext(source_unicode)
+            content = source.strip().encode("utf-8") # + "\n"
             #content = content.rstrip() + "\n"
             p.write(content, "wb")
             if ret is None:
diff --git a/testing/test_assertrewrite.py b/testing/test_assertrewrite.py
index 06288e899..d19879527 100644
--- a/testing/test_assertrewrite.py
+++ b/testing/test_assertrewrite.py
@@ -458,28 +458,29 @@ class TestAssertionRewriteHookDetails(object):
 
     @pytest.mark.skipif("sys.version_info[0] >= 3")
     def test_detect_coding_cookie(self, testdir):
-        testdir.tmpdir.join("test_cookie.py").write("""# -*- coding: utf-8 -*-
-u"St\xc3\xa4d"
-def test_rewritten():
-    assert "@py_builtins" in globals()""", "wb")
+        testdir.makepyfile(test_cookie=u"""
+            # -*- coding: utf-8 -*-
+            u"St\xc3\xa4d"
+            def test_rewritten():
+                assert "@py_builtins" in globals()""".encode('utf-8'))
         assert testdir.runpytest().ret == 0
 
     @pytest.mark.skipif("sys.version_info[0] >= 3")
     def test_detect_coding_cookie_second_line(self, testdir):
-        testdir.tmpdir.join("test_cookie.py").write("""#!/usr/bin/env python
-# -*- coding: utf-8 -*-
-u"St\xc3\xa4d"
-def test_rewritten():
-    assert "@py_builtins" in globals()""", "wb")
+        testdir.makepyfile(test_cookie=u"""
+            # -*- coding: utf-8 -*-
+            u"St\xc3\xa4d"
+            def test_rewritten():
+                assert "@py_builtins" in globals()""".encode('utf-8'))
         assert testdir.runpytest().ret == 0
 
     @pytest.mark.skipif("sys.version_info[0] >= 3")
     def test_detect_coding_cookie_crlf(self, testdir):
-        testdir.tmpdir.join("test_cookie.py").write("""#!/usr/bin/env python
-# -*- coding: utf-8 -*-
-u"St\xc3\xa4d"
-def test_rewritten():
-    assert "@py_builtins" in globals()""".replace("\n", "\r\n"), "wb")
+        testdir.makepyfile(test_cookie=u"""
+            # -*- coding: utf-8 -*-
+            u"St\xc3\xa4d"
+            def test_rewritten():
+                assert "@py_builtins" in globals()""".encode('utf-8'))
         assert testdir.runpytest().ret == 0
 
     def test_sys_meta_path_munged(self, testdir):