diff --git a/.circleci/config.yml b/.circleci/config.yml
index 89819c10..858ca001 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -12,6 +12,7 @@ jobs:
             - run: sudo python -m spacy download en
             - run: python -m pytest -sv ./pytorch_pretrained_bert/tests/ --cov
             - run: codecov
+        parallelism: 4
     build_py2:
         working_directory: ~/pytorch-pretrained-BERT
         docker:
@@ -24,6 +25,7 @@ jobs:
             - run: sudo python -m spacy download en
             - run: python -m pytest -sv ./pytorch_pretrained_bert/tests/ --cov
             - run: codecov
+        parallelism: 4
 workflows:
   version: 2
   build_and_test: