diff --git a/src/tox/session/cmd/run/parallel.py b/src/tox/session/cmd/run/parallel.py
index 9931bd3c16..d83d72a24e 100644
--- a/src/tox/session/cmd/run/parallel.py
+++ b/src/tox/session/cmd/run/parallel.py
@@ -53,7 +53,7 @@ def parallel_flags(
     default_parallel: int | str,
     no_args: bool = False,  # noqa: FBT001, FBT002
     *,
-    default_spinner: bool | None = None,
+    default_spinner: bool = False,
 ) -> None:
     our.add_argument(
         "-p",