diff --git a/README b/README
index ccb46b46d..09e29e1d4 100644
--- a/README
+++ b/README
@@ -21,7 +21,7 @@ https://github.com/milkymist/migen
 Experimental version of the Milkymist SoC based on Migen:
 https://github.com/milkymist/milkymist-ng
 
-Mibuild is designed for Python 3.
+Mibuild is designed for Python 3.3.
 
 Send questions, comments and patches to devel [AT] lists.milkymist.org
 Description files for new boards welcome.
diff --git a/setup.py b/setup.py
index 246957127..76cc0bc46 100755
--- a/setup.py
+++ b/setup.py
@@ -7,7 +7,7 @@ from setuptools import find_packages
 here = os.path.abspath(os.path.dirname(__file__))
 README = open(os.path.join(here, "README")).read()
 
-required_version = (3, 1)
+required_version = (3, 3)
 if sys.version_info < required_version:
 	raise SystemExit("Mibuild requires python {0} or greater".format(
 		".".join(map(str, required_version))))