diff --git a/tox.ini b/tox.ini
index 2f6956f5b..6ebf681ed 100644
--- a/tox.ini
+++ b/tox.ini
@@ -11,9 +11,8 @@ envlist = modification,py{26,33,34,35,36},cover,lint
 pip_install = {toxinidir}/tools/pip_install_editable.sh
 # pip installs the requested packages in editable mode and runs unit tests on
 # them. Each package is installed and tested in the order they are provided
-# before the script moves on to the next package. If CERTBOT_NO_PIN is set not
-# set to 1, packages are installed using certbot-auto's requirements file as
-# constraints.
+# before the script moves on to the next package. All dependencies are pinned
+# to a specific version for increased stability for developers.
 install_and_test = {toxinidir}/tools/install_and_test.sh
 py26_packages =
     acme[dev] \
@@ -82,33 +81,7 @@ commands =
     {[testenv]commands}
 setenv =
     {[testenv]setenv}
-    CERTBOT_NO_PIN=1
-deps =
-    PyOpenSSL==0.13
-    cffi==1.5.2
-    configargparse==0.10.0
-    configargparse==0.10.0
-    configobj==4.7.2
-    cryptography==1.2.3
-    enum34==0.9.23
-    idna==2.0
-    ipaddress==1.0.16
-    mock==1.0.1
-    ndg-httpsclient==0.3.2
-    parsedatetime==1.4
-    pyasn1==0.1.9
-    pyparsing==1.5.6
-    pyrfc3339==1.0
-    pytest==3.2.5
-    python-augeas==0.4.1
-    pytz==2012c
-    requests[security]==2.6.0
-    setuptools==0.9.8
-    six==1.9.0
-    urllib3==1.10
-    zope.component==4.0.2
-    zope.event==4.0.1
-    zope.interface==4.0.5
+    CERTBOT_OLDEST=1
 
 [testenv:py27_install]
 basepython = python2.7