diff --git a/_pytest/config.py b/_pytest/config.py
index 555799658..e573ec8ab 100644
--- a/_pytest/config.py
+++ b/_pytest/config.py
@@ -495,7 +495,7 @@ FILE_OR_DIR = 'file_or_dir'
 class Config(object):
     """ access to configuration values, pluginmanager and plugin hooks.  """
 
-    def __init__(self, pluginmanager=None):
+    def __init__(self, pluginmanager):
         #: access to command line option as attributes.
         #: (deprecated), use :py:func:`getoption() <_pytest.config.Config.getoption>` instead
         self.option = CmdOptions()
@@ -505,7 +505,7 @@ class Config(object):
             processopt=self._processopt,
         )
         #: a pluginmanager instance
-        self.pluginmanager = pluginmanager or PluginManager(load=True)
+        self.pluginmanager = pluginmanager
         self.trace = self.pluginmanager.trace.root.get("config")
         self._conftest = Conftest(onimport=self._onimportconftest)
         self.hook = self.pluginmanager.hook
@@ -516,7 +516,7 @@ class Config(object):
     @classmethod
     def fromdictargs(cls, option_dict, args):
         """ constructor useable for subprocesses. """
-        config = cls()
+        config = cls(PluginManager(load=True))
         # XXX slightly crude way to initialize capturing
         import _pytest.capture
         _pytest.capture.pytest_cmdline_parse(config.pluginmanager, args)
diff --git a/testing/test_config.py b/testing/test_config.py
index 1e3eb6d70..912ebbe83 100644
--- a/testing/test_config.py
+++ b/testing/test_config.py
@@ -82,7 +82,7 @@ class TestConfigCmdlineParsing:
 
 class TestConfigAPI:
     def test_config_trace(self, testdir):
-        config = testdir.Config()
+        config = testdir.parseconfig()
         l = []
         config.trace.root.setwriter(l.append)
         config.trace("hello")
diff --git a/testing/test_core.py b/testing/test_core.py
index 0a18a8efc..8a960228b 100644
--- a/testing/test_core.py
+++ b/testing/test_core.py
@@ -319,7 +319,7 @@ class TestPytestPluginInteractions:
             def pytest_myhook(xyz):
                 return xyz + 1
         """)
-        config = testdir.Config()
+        config = testdir.Config(PluginManager(load=True))
         config._conftest.importconftest(conf)
         print(config.pluginmanager.getplugins())
         res = config.hook.pytest_myhook(xyz=10)
diff --git a/testing/test_tmpdir.py b/testing/test_tmpdir.py
index 164ee68c6..6ec790283 100644
--- a/testing/test_tmpdir.py
+++ b/testing/test_tmpdir.py
@@ -36,7 +36,7 @@ def test_ensuretemp(recwarn):
 
 class TestTempdirHandler:
     def test_mktemp(self, testdir):
-        config = testdir.Config()
+        config = testdir.parseconfig()
         config.option.basetemp = testdir.mkdir("hello")
         t = TempdirHandler(config)
         tmp = t.mktemp("world")