diff --git a/src/tox/config/__init__.py b/src/tox/config/__init__.py
index b49c06f6d..36748e041 100644
--- a/src/tox/config/__init__.py
+++ b/src/tox/config/__init__.py
@@ -245,7 +245,7 @@ def postprocess(self, testenv_config, value):
 class InstallcmdOption:
     name = "install_command"
     type = "argv_install_command"
-    default = r"python -m pip install \{opts\} \{packages\}"
+    default = r"python -Xutf8 -m pip install \{opts\} \{packages\}"
     help = "install command for dependencies and package under test."
 
     def postprocess(self, testenv_config, value):
diff --git a/src/tox/venv.py b/src/tox/venv.py
index 13235c8a9..d8bccddac 100644
--- a/src/tox/venv.py
+++ b/src/tox/venv.py
@@ -717,7 +717,7 @@ def prepend_shebang_interpreter(args):
 @tox.hookimpl
 def tox_testenv_create(venv, action):
     config_interpreter = venv.getsupportedinterpreter()
-    args = [sys.executable, "-m", "virtualenv"]
+    args = [sys.executable, "-Xutf8", "-m", "virtualenv"]
     if venv.envconfig.sitepackages:
         args.append("--system-site-packages")
     if venv.envconfig.alwayscopy: