diff --git a/tests/test_trioisms.py b/tests/test_trioisms.py
index 7f6caa6e..e6c42c01 100644
--- a/tests/test_trioisms.py
+++ b/tests/test_trioisms.py
@@ -117,7 +117,6 @@ def test_acm_embedded_nursery_propagates_enter_err(
         async with (
             trio.open_nursery() as tn,
             tractor.trionics.maybe_raise_from_masking_exc(
-                tn=tn,
                 unmask_from=(
                     (trio.Cancelled,) if unmask_from_canc
                     else ()
diff --git a/tractor/_rpc.py b/tractor/_rpc.py
index 0be4e6a9..023bae17 100644
--- a/tractor/_rpc.py
+++ b/tractor/_rpc.py
@@ -673,7 +673,6 @@ async def _invoke(
                 # scope ensures unasking of the `await coro` below
                 # *should* never be interfered with!!
                 maybe_raise_from_masking_exc(
-                    tn=tn,
                     unmask_from=(Cancelled,),
                 ) as _mbme,  # maybe boxed masked exc
             ):
diff --git a/tractor/trionics/_taskc.py b/tractor/trionics/_taskc.py
index fb743bbc..4e336b59 100644
--- a/tractor/trionics/_taskc.py
+++ b/tractor/trionics/_taskc.py
@@ -65,7 +65,6 @@ def find_masked_excs(
 #
 @acm
 async def maybe_raise_from_masking_exc(
-    tn: trio.Nursery|None = None,
     unmask_from: (
         BaseException|
         tuple[BaseException]