diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index ef8debb3fb7..1db9f5d6d93 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -42,7 +42,7 @@ jobs:
 
       - name: Unit tests
         run: |
-          tox -e py -- -v --color=yes
+          tox -e ci-py -- -v --color=yes
 
       - name: Publish coverage to Coveralls
         # If pushed / is a pull request against main repo AND
diff --git a/tox.ini b/tox.ini
index 2379500f55a..3ea4da8eac2 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,17 +1,23 @@
 [tox]
-envlist = py{36,37,38,39},fuzz
+envlist = {,ci-}py{36,37,38,39},fuzz
 
 [testenv]
 setenv = PYTHONPATH = {toxinidir}/src
 skip_install = True
 deps =
     -r{toxinidir}/test_requirements.txt
+; parallelization is disabled on CI because pytest-dev/pytest-xdist#620 occurs too frequently
+; local runs can stay parallelized since they aren't rolling the dice so many times as like on CI
 commands =
     pip install -e .[d]
     coverage erase
-    pytest tests --run-optional no_python2 --numprocesses auto --cov {posargs}
+    pytest tests --run-optional no_python2 \
+        !ci: --numprocesses auto \
+        --cov {posargs}
     pip install -e .[d,python2]
-    pytest tests --run-optional python2 --numprocesses auto --cov --cov-append {posargs}
+    pytest tests --run-optional python2 \
+        !ci: --numprocesses auto \
+        --cov --cov-append {posargs}
     coverage report
 
 [testenv:fuzz]