diff --git a/tox.ini b/tox.ini
index f32d9325..c53938d9 100644
--- a/tox.ini
+++ b/tox.ini
@@ -23,7 +23,7 @@ commands = python -m pytest {posargs}
 
 [testenv:py27]
 extras = {env:TOX_AP_TEST_EXTRAS:tests}
-commands = coverage run --parallel -m pytest {posargs}
+commands = coverage run -m pytest {posargs}
 
 
 [testenv:py37]
@@ -33,7 +33,7 @@ install_command = pip install --no-compile {opts} {packages}
 setenv =
     PYTHONWARNINGS=d
 extras = {env:TOX_AP_TEST_EXTRAS:tests}
-commands = coverage run --parallel -m pytest {posargs}
+commands = coverage run -m pytest {posargs}
 
 
 [testenv:py38]
@@ -44,7 +44,7 @@ install_command = pip install --no-compile {opts} {packages}
 setenv =
     PYTHONWARNINGS=d
 extras = {env:TOX_AP_TEST_EXTRAS:tests}
-commands = coverage run --parallel -m pytest {posargs}
+commands = coverage run -m pytest {posargs}
 
 
 [testenv:coverage-report]