1 files changed, 1 insertions, 1 deletions
diff --git a/tox.ini b/tox.ini
index 1d7dcac..3970462 100644
--- a/tox.ini
+++ b/tox.ini
@@ -13,7 +13,7 @@ setenv =
     # Do not allow the executing environment to pollute the test environment
     # with extra packages.
     PYTHONPATH=
-    PIP_NO_BINARY=:all:
+    PIP_NO_BINARY=cryptography
 commands =
     openssl version
     python -c "import OpenSSL.SSL; print(OpenSSL.SSL.SSLeay_version(OpenSSL.SSL.SSLEAY_VERSION))"