diff --git a/src/_pytest/config/__init__.py b/src/_pytest/config/__init__.py
index ec3fc6afe..7468d2c31 100644
--- a/src/_pytest/config/__init__.py
+++ b/src/_pytest/config/__init__.py
@@ -769,7 +769,7 @@ class Config:
         self,
         pluginmanager: PytestPluginManager,
         *,
-        invocation_params: InvocationParams = None
+        invocation_params: Optional[InvocationParams] = None
     ) -> None:
         from .argparsing import Parser, FILE_OR_DIR