diff --git a/requirements.txt b/requirements.txt
index 1b6de23..4a584e6 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -23,7 +23,7 @@ eth-hash[pycryptodome]==0.2.0
 eth-keyfile==0.5.1
 eth-keys==0.2.0b3
 eth-rlp==0.1.2
-eth-tester==0.1.0b33
+eth-tester[py-evm]==0.1.0b33
 eth-typing==1.3.0
 eth-utils==1.3.0
 hexbytes==0.2.0           # via eth-account, eth-rlp, web3
diff --git a/tox.ini b/tox.ini
index 209ed7b..3e7973c 100644
--- a/tox.ini
+++ b/tox.ini
@@ -7,6 +7,7 @@ setenv =
     LC_ALL=en_US.utf-8
     LANG=en_US.utf-8
 deps =
+    pytest
     -r{toxinidir}/requirements.txt
 commands =
     pip freeze