Document the requirement for PyTest 2.8.6 or above.
Fixes #43.
diff --git a/README.md b/README.md
index 7260562..c72f2ed 100644
--- a/README.md
+++ b/README.md
@@ -51,7 +51,9 @@
## Installation
### Compatibility
-pyfakefs works with Python 2.6 and above. pyfakefs requires [mox3](https://pypi.python.org/pypi/mox3).
+pyfakefs works with Python 2.6 and above, on Linux and Windows. pyfakefs requires [mox3](https://pypi.python.org/pypi/mox3).
+
+When using pyfakefs with [PyTest](doc.pytest.org), Pytest version 2.8.6 or above is required.
### PyPi
[pyfakefs is available on PyPi](https://pypi.python.org/pypi/pyfakefs/).
diff --git a/pytest_doctest_test.py b/pytest_doctest_test.py
index 5098dc6..b580b96 100644
--- a/pytest_doctest_test.py
+++ b/pytest_doctest_test.py
@@ -1,5 +1,6 @@
"""
This is a test case for pyfakefs issue #45.
+This problem is resolved by using PyTest version 2.8.6 or above.
To run these doctests, install pytest and run:
