diff --git a/tools/install_and_test.py b/tools/install_and_test.py
index 0142eeea4..b15c8eca5 100755
--- a/tools/install_and_test.py
+++ b/tools/install_and_test.py
@@ -49,7 +49,7 @@ def main(args):
         shutil.copy2("pytest.ini", temp_cwd)
         try:
             call_with_print(' '.join([
-                sys.executable, '-m', 'pytest', pkg.replace('-', '_')]), cwd=temp_cwd)
+                sys.executable, '-m', 'pytest', '--pyargs', pkg.replace('-', '_')]), cwd=temp_cwd)
         finally:
             shutil.rmtree(temp_cwd)
 
diff --git a/tox.cover.py b/tox.cover.py
index c8a45d82d..008424641 100755
--- a/tox.cover.py
+++ b/tox.cover.py
@@ -48,8 +48,8 @@ def cover(package):
             .format(pkg_dir)))
         return
 
-    subprocess.check_call([
-        sys.executable, '-m', 'pytest', '--cov', pkg_dir, '--cov-append', '--cov-report=', package])
+    subprocess.check_call([sys.executable, '-m', 'pytest', '--pyargs',
+                           '--cov', pkg_dir, '--cov-append', '--cov-report=', package])
     subprocess.check_call([
         sys.executable, '-m', 'coverage', 'report', '--fail-under', str(threshold), '--include',
         '{0}/*'.format(pkg_dir), '--show-missing'])
diff --git a/tox.ini b/tox.ini
index 76de2ea36..b66e330da 100644
--- a/tox.ini
+++ b/tox.ini
@@ -70,7 +70,7 @@ commands =
     {[base]install_and_test} {[base]all_packages}
     python tests/lock_test.py
 setenv =
-    PYTEST_ADDOPTS = {env:PYTEST_ADDOPTS:--numprocesses auto --pyargs}
+    PYTEST_ADDOPTS = {env:PYTEST_ADDOPTS:--numprocesses auto}
     PYTHONHASHSEED = 0
 
 [testenv:py27-oldest]