diff --git a/tox.ini b/tox.ini
index 8b0841f..2dd1039 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,7 +1,9 @@
 [tox]
 envlist = py27,pypy,py34,flake8
 [testenv:py27]
+whitelist_externals = rm
 commands = 
+    rm -f jellyfish/cjellyfish.so
     pip install -e .
     py.test jellyfish/test.py
 deps = pytest
@@ -13,7 +15,9 @@ commands =
 deps = pytest
     unicodecsv
 [testenv:py34]
+whitelist_externals = rm
 commands = 
+    rm -f jellyfish/cjellyfish.so
     pip install -e .
     py.test jellyfish/test.py
 deps = pytest