diff --git a/tox.ini b/tox.ini
index 87a56f842..16dbaed90 100644
--- a/tox.ini
+++ b/tox.ini
@@ -21,23 +21,30 @@ envlist =
 
 [testenv]
 commands =
-    {env:_PYTEST_TOX_COVERAGE_RUN:} pytest {env:_PYTEST_TOX_ARGS:} {posargs}
+    {env:_PYTEST_TOX_COVERAGE_RUN:} pytest {posargs:{env:_PYTEST_TOX_DEFAULT_POSARGS}}
     coverage: coverage combine
     coverage: coverage report
 passenv = USER USERNAME COVERAGE_* TRAVIS PYTEST_ADDOPTS
 setenv =
-    _PYTEST_TOX_ARGS=--lsof
+    _PYTEST_TOX_DEFAULT_POSARGS=--lsof
+
     # Configuration to run with coverage similar to Travis/Appveyor, e.g.
     # "tox -e py37-coverage".
     coverage: _PYTEST_TOX_COVERAGE_RUN=coverage run -m
     coverage: _PYTEST_TOX_EXTRA_DEP=coverage-enable-subprocess
     coverage: COVERAGE_FILE={toxinidir}/.coverage
     coverage: COVERAGE_PROCESS_START={toxinidir}/.coveragerc
-    xdist: _PYTEST_TOX_ARGS={env:_PYTEST_TOX_ARGS:-n auto}
+
+    pexpect: _PYTEST_TOX_PLATFORM=linux|darwin
+    pexpect: _PYTEST_TOX_DEFAULT_POSARGS={env:_PYTEST_TOX_DEFAULT_POSARGS:testing/test_pdb.py testing/test_terminal.py testing/test_unittest.py}
+
+    xdist: _PYTEST_TOX_DEFAULT_POSARGS={env:_PYTEST_TOX_DEFAULT_POSARGS:-n auto}
 extras = testing
 deps =
+    pexpect: pexpect
     xdist: pytest-xdist>=1.13
     {env:_PYTEST_TOX_EXTRA_DEP:}
+platform = {env:_PYTEST_TOX_PLATFORM:.*}
 
 [testenv:py27-subprocess]
 deps =
@@ -54,19 +61,6 @@ basepython = python3
 deps = pre-commit>=1.11.0
 commands = pre-commit run --all-files --show-diff-on-failure
 
-[testenv:py27-pexpect]
-platform = linux|darwin
-deps =
-    {[testenv]deps}
-    pexpect
-commands =
-    {env:_PYTEST_TOX_COVERAGE_RUN:} pytest {posargs:testing/test_pdb.py testing/test_terminal.py testing/test_unittest.py}
-
-[testenv:py37-pexpect]
-platform = {[testenv:py27-pexpect]platform}
-deps = {[testenv:py27-pexpect]deps}
-commands = {[testenv:py27-pexpect]commands}
-
 [testenv:py27-nobyte]
 extras = testing
 deps =