1 files changed, 1 insertions, 0 deletions

diff --git a/tox.ini b/tox.ini
index 607b182..ace1ba9 100644
--- a/tox.ini
+++ b/tox.ini
@@ -5,6 +5,7 @@ envlist =
     {pypy,pypy3}-pure,
     py27-x86,
     py34-x86,
+isolated_build = true
 
 [variants:pure]
 setenv=