diff --git a/tests/conftest.py b/tests/conftest.py
index 22d1af3c..2ffc3d0f 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -92,8 +92,7 @@ def log(
 @acm
 async def _open_test_pikerd(
     tmpconfdir: str,
-
-    reg_addr: tuple[str, int] | None = None,
+    reg_addr: tuple[str, int|str],
     loglevel: str = 'warning',
     debug_mode: bool = False,
 
@@ -113,16 +112,10 @@ async def _open_test_pikerd(
     to boot the root actor / tractor runtime.
 
     '''
-    import random
     from piker.service import maybe_open_pikerd
-
-    if reg_addr is None:
-        port = random.randint(6e3, 7e3)
-        reg_addr = ('127.0.0.1', port)
-
     async with (
         maybe_open_pikerd(
-            registry_addr=reg_addr,
+            registry_addrs=[reg_addr],
             loglevel=loglevel,
 
             tractor_runtime_overrides={
@@ -139,13 +132,15 @@ async def _open_test_pikerd(
 
         async with tractor.wait_for_actor(
             'pikerd',
-            arbiter_sockaddr=reg_addr,
+            registry_addr=reg_addr,
         ) as portal:
-            raddr = portal.channel.raddr
-            assert raddr == reg_addr
+            raddr = portal.chan.raddr
+            uw_raddr: tuple = raddr.unwrap()
+            assert uw_raddr == reg_addr
+            await tractor.pause()
             yield (
-                raddr[0],
-                raddr[1],
+                raddr._host,
+                raddr._port,
                 portal,
                 service_manager,
             )
@@ -202,7 +197,10 @@ def open_test_pikerd(
     request: pytest.FixtureRequest,
     tmp_path: Path,
     tmpconfdir: Path,
+
+    # XXX from `tractor._testing.pytest` plugin
     loglevel: str,
+    reg_addr: tuple,
 ):
 
     tmpconfdir_str: str = str(tmpconfdir)
@@ -236,10 +234,13 @@ def open_test_pikerd(
         # bwitout clobbering each other's config state.
         tmpconfdir=tmpconfdir_str,
 
-        # bind in level from fixture, which is itself set by
-        # `--ll <value>` cli flag.
+        # NOTE these come verbatim from `tractor`'s builtin plugin!
+        #
+        # per-tpt compat registrar address.
+        reg_addr=reg_addr,
+        # bind in level from fixture.
+        # (can be set with `--ll <value>` flag to `pytest`).
         loglevel=loglevel,
-
         debug_mode=debug_mode,
     )