diff --git a/tractor/msg.py b/tractor/msg.py
index f778ac7..4184333 100644
--- a/tractor/msg.py
+++ b/tractor/msg.py
@@ -11,7 +11,6 @@ import trio
 import wrapt
 
 from .log import get_logger
-from . import current_actor
 from ._streaming import Context
 
 __all__ = ['pub']
@@ -91,6 +90,7 @@ def modify_subs(topics2ctxs, topics, ctx):
 
 
 _pub_state: Dict[str, dict] = {}
+_pubtask2lock: Dict[str, dict] = {}
 
 
 def pub(
@@ -178,22 +178,22 @@ def pub(
     subscribers. If you are ok to have a new task running for every call
     to ``pub_service()`` then probably don't need this.
     """
-    global _pub_state
+    global _pubtask2lock
 
     # handle the decorator not called with () case
     if wrapped is None:
         return partial(pub, tasks=tasks)
 
-    task2lock: Dict[Union[str, None], trio.StrictFIFOLock] = {
-        None: trio.StrictFIFOLock()}
+    task2lock: Dict[Union[str, None], trio.StrictFIFOLock] = {}
 
     for name in tasks:
         task2lock[name] = trio.StrictFIFOLock()
 
     @wrapt.decorator
     async def wrapper(agen, instance, args, kwargs):
-        # this is used to extract arguments properly as per
-        # the `wrapt` docs
+
+        # XXX: this is used to extract arguments properly as per the
+        # `wrapt` docs
         async def _execute(
             ctx: Context,
             topics: Set[str],
@@ -203,14 +203,22 @@ def pub(
             packetizer: Callable = None,
             **kwargs,
         ):
-            if tasks and task_name is None:
+            if task_name is None:
+                task_name = trio.lowlevel.current_task().name
+
+            if tasks and task_name not in tasks:
                 raise TypeError(
                     f"{agen} must be called with a `task_name` named "
-                    f"argument with a falue from {tasks}")
+                    f"argument with a value from {tasks}")
+
+            elif not tasks and not task2lock:
+                # add a default root-task lock if none defined
+                task2lock[task_name] = trio.StrictFIFOLock()
+
+            _pubtask2lock.update(task2lock)
 
             topics = set(topics)
-            lockmap = _pub_state.setdefault('_pubtask2lock', task2lock)
-            lock = lockmap[task_name]
+            lock = _pubtask2lock[task_name]
 
             all_subs = _pub_state.setdefault('_subs', {})
             topics2ctxs = all_subs.setdefault(task_name, {})