1 files changed, 2 insertions, 1 deletions
diff --git a/tox.ini b/tox.ini
index bb237f83..8f60ac31 100644
--- a/tox.ini
+++ b/tox.ini
@@ -16,7 +16,7 @@ deps =
     pip==18.1
     setuptools==40.6.3
     # gevent 1.3 causes a failure: https://github.com/nedbat/coveragepy/issues/663
-    py{27,34,35,36}: gevent==1.2.2
+    py{27,34,35,36}: gevent==1.3.7
     py{27,34,35,36,37,38}: eventlet==0.24.1
     py{27,34,35,36,37,38}: greenlet==0.4.15
 
@@ -26,6 +26,7 @@ install_command = python -m pip install -U {opts} {packages}
 
 passenv = *
 setenv =
+    GEVENT_LOOP=libev-cext
     pypy,pypy{2,3}: COVERAGE_NO_CTRACER=no C extension under PyPy
     jython: COVERAGE_NO_CTRACER=no C extension under Jython
     jython: PYTEST_ADDOPTS=-n 0