diff --git a/tractor/_root.py b/tractor/_root.py
index 39a7880c..97bf7062 100644
--- a/tractor/_root.py
+++ b/tractor/_root.py
@@ -145,11 +145,16 @@ async def maybe_block_bp(
 @acm
 async def open_root_actor(
     *,
-    # defaults are above
-    registry_addrs: list[UnwrappedAddress]|None = None,
+    tpt_bind_addrs: list[
+        Address  # `Address.get_random()` case
+        |UnwrappedAddress  # registrar case `= uw_reg_addrs`
+    ]|None = None,
 
     # defaults are above
-    arbiter_addr: tuple[UnwrappedAddress]|None = None,
+    registry_addrs: list[
+        Address
+        |UnwrappedAddress
+    ]|None = None,
 
     enable_transports: list[
         # TODO, this should eventually be the pairs as
@@ -268,15 +273,7 @@ async def open_root_actor(
         if start_method is not None:
             _spawn.try_set_start_method(start_method)
 
-        if arbiter_addr is not None:
-            warnings.warn(
-                '`arbiter_addr` is now deprecated\n'
-                'Use `registry_addrs: list[tuple]` instead..',
-                DeprecationWarning,
-                stacklevel=2,
-            )
-            uw_reg_addrs = [arbiter_addr]
-
+        # XXX expect pre-unwrapped registrar addrs.
         uw_reg_addrs = registry_addrs
         if not uw_reg_addrs:
             uw_reg_addrs: list[UnwrappedAddress] = default_lo_addrs(
@@ -289,7 +286,6 @@ async def open_root_actor(
             wrap_address(uw_addr)
             for uw_addr in uw_reg_addrs
         ]
-
         loglevel: str = (
             loglevel
             or
@@ -386,10 +382,14 @@ async def open_root_actor(
                     addr,
                 )
 
-        tpt_bind_addrs: list[
-            Address  # `Address.get_random()` case
-            |UnwrappedAddress  # registrar case `= uw_reg_addrs`
-        ] = []
+        if tpt_bind_addrs is None:
+            tpt_bind_addrs: list[Address] = []
+        else:
+            input_bind_addrs = list(tpt_bind_addrs)
+            tpt_bind_addrs: list[Address] = []
+            for addr in input_bind_addrs:
+                addr: Address = wrap_address(addr)
+                tpt_bind_addrs.append(addr)
 
         # ------ NON-REGISTRAR ------
         # create a new root-actor instance.
@@ -417,19 +417,20 @@ async def open_root_actor(
             # a new NON-registrar, ROOT-actor.
             #
             # XXX INSTEAD, bind random addrs using the same tpt
-            # proto.
-            for addr in ponged_addrs:
-                tpt_bind_addrs.append(
-                    # XXX, these are `Address` NOT `UnwrappedAddress`.
-                    #
-                    # NOTE, in the case of posix/berkley socket
-                    # protos we allocate port=0 such that the system
-                    # allocates a random value at bind time; this
-                    # happens in the `.ipc.*` stack's backend.
-                    addr.get_random(
-                        bindspace=addr.bindspace,
+            # proto if not already provided.
+            if not tpt_bind_addrs:
+                for addr in ponged_addrs:
+                    tpt_bind_addrs.append(
+                        # XXX, these are `Address` NOT `UnwrappedAddress`.
+                        #
+                        # NOTE, in the case of posix/berkley socket
+                        # protos we allocate port=0 such that the system
+                        # allocates a random value at bind time; this
+                        # happens in the `.ipc.*` stack's backend.
+                        addr.get_random(
+                            bindspace=addr.bindspace,
+                        )
                     )
-                )
 
         # ------ REGISTRAR ------
         # create a new "registry providing" root-actor instance.
@@ -442,7 +443,11 @@ async def open_root_actor(
             # following init steps are taken:
             # - the tranport layer server is bound to each addr
             #   pair defined in provided registry_addrs, or the default.
-            tpt_bind_addrs = uw_reg_addrs
+            tpt_bind_addrs = list(set(
+                tpt_bind_addrs
+                +
+                uw_reg_addrs
+            ))
 
             # - it is normally desirable for any registrar to stay up
             #   indefinitely until either all registered (child/sub)
diff --git a/tractor/runtime/_runtime.py b/tractor/runtime/_runtime.py
index 074c339a..618d33da 100644
--- a/tractor/runtime/_runtime.py
+++ b/tractor/runtime/_runtime.py
@@ -1564,7 +1564,15 @@ async def async_main(
                     addr: Address = transport_cls.get_random()
                     accept_addrs.append(addr.unwrap())
 
-        assert accept_addrs
+        # XXX, either passed in by caller or delivered
+        # in post spawn-spec handshake for subs.
+        if not accept_addrs:
+            RuntimeError(
+                f'No tpt bind addresses provided to actor!?\n'
+                f'parent_addr={parent_addr!r}\n'
+                f'accept_addrs={accept_addrs!r}\n'
+                f'enable_transports={enable_transports!r}\n'
+            )
 
         ya_root_tn: bool = bool(actor._root_tn)
         ya_service_tn: bool = bool(actor._service_tn)