diff --git a/tox.ini b/tox.ini
index 8aa4bfbf2..05535a6f9 100644
--- a/tox.ini
+++ b/tox.ini
@@ -39,24 +39,42 @@ install_packages =
     python {toxinidir}/tools/pip_install_editable.py {[base]all_packages}
 source_paths =
     acme/acme
+    acme/tests
     certbot/certbot
+    certbot/tests
     certbot-apache/certbot_apache
+    certbot-apache/tests
     certbot-compatibility-test/certbot_compatibility_test
     certbot-dns-cloudflare/certbot_dns_cloudflare
+    certbot-dns-cloudflare/tests
     certbot-dns-cloudxns/certbot_dns_cloudxns
+    certbot-dns-cloudxns/tests
     certbot-dns-digitalocean/certbot_dns_digitalocean
+    certbot-dns-digitalocean/tests
     certbot-dns-dnsimple/certbot_dns_dnsimple
+    certbot-dns-dnsimple/tests
     certbot-dns-dnsmadeeasy/certbot_dns_dnsmadeeasy
+    certbot-dns-dnsmadeeasy/tests
     certbot-dns-gehirn/certbot_dns_gehirn
+    certbot-dns-gehirn/tests
     certbot-dns-google/certbot_dns_google
+    certbot-dns-google/tests
     certbot-dns-linode/certbot_dns_linode
+    certbot-dns-linode/tests
     certbot-dns-luadns/certbot_dns_luadns
+    certbot-dns-luadns/tests
     certbot-dns-nsone/certbot_dns_nsone
+    certbot-dns-nsone/tests
     certbot-dns-ovh/certbot_dns_ovh
+    certbot-dns-ovh/tests
     certbot-dns-rfc2136/certbot_dns_rfc2136
+    certbot-dns-rfc2136/tests
     certbot-dns-route53/certbot_dns_route53
+    certbot-dns-route53/tests
     certbot-dns-sakuracloud/certbot_dns_sakuracloud
+    certbot-dns-sakuracloud/tests
     certbot-nginx/certbot_nginx
+    certbot-nginx/tests
     tests/lock_test.py
 
 [testenv]
@@ -145,7 +163,7 @@ basepython = python3
 commands =
     {[base]install_packages}
     {[base]pip_install} certbot[dev3]
-    mypy {[base]source_paths}
+    mypy {[base]source_paths} --config-file {toxinidir}/mypy.ini
 
 [testenv:apacheconftest]
 commands =