diff --git a/tox.ini b/tox.ini
index 1217f4032..da5ae9fec 100644
--- a/tox.ini
+++ b/tox.ini
@@ -12,7 +12,7 @@ envlist =
     py36
     py37
     pypy
-    {py27,py35}-{pexpect,xdist,trial}
+    {py27,py35}-{pexpect,xdist,trial,numpy}
     py27-nobyte
     doctesting
     freeze