Closes #279: setuptools.version is too new.
diff --git a/setup.py b/setup.py
index 52921a2..161016b 100755
--- a/setup.py
+++ b/setup.py
@@ -7,7 +7,7 @@
 # Setuptools 17.1 is required, and setup_requires cannot upgrade setuptools
 # in-place, nor trigger the use of a newer version. Abort cleanly up-front.
 setuptools_required = StrictVersion("17.1")
-setuptools_installed = StrictVersion(setuptools.version.__version__)
+setuptools_installed = StrictVersion(setuptools.__version__)
 if setuptools_installed < setuptools_required:
     sys.stderr.write(
         "mock requires setuptools>=17.1. Aborting installation\n")