diff --git a/tests/conftest.py b/tests/conftest.py
index 3363cf5..8e9a67c 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -29,7 +29,7 @@ def tractor_test(fn):
 
     If fixtures:
 
-        - ``arb_addr`` (a socket addr tuple where arbiter is listening)
+        - ``reg_addr`` (a socket addr tuple where arbiter is listening)
         - ``loglevel`` (logging level passed to tractor internals)
         - ``start_method`` (subprocess spawning backend)
 
@@ -40,16 +40,16 @@ def tractor_test(fn):
     def wrapper(
         *args,
         loglevel=None,
-        arb_addr=None,
+        reg_addr=None,
         start_method=None,
         **kwargs
     ):
         # __tracebackhide__ = True
 
-        if 'arb_addr' in inspect.signature(fn).parameters:
+        if 'reg_addr' in inspect.signature(fn).parameters:
             # injects test suite fixture value to test as well
             # as `run()`
-            kwargs['arb_addr'] = arb_addr
+            kwargs['reg_addr'] = reg_addr
 
         if 'loglevel' in inspect.signature(fn).parameters:
             # allows test suites to define a 'loglevel' fixture
@@ -71,7 +71,7 @@ def tractor_test(fn):
             async def _main():
                 async with tractor.open_root_actor(
                     # **kwargs,
-                    arbiter_addr=arb_addr,
+                    registry_addrs=[reg_addr] if reg_addr else None,
                     loglevel=loglevel,
                     start_method=start_method,
 
@@ -92,9 +92,6 @@ def tractor_test(fn):
     return wrapper
 
 
-_arb_addr = '127.0.0.1', random.randint(1000, 9999)
-
-
 # Sending signal.SIGINT on subprocess fails on windows. Use CTRL_* alternatives
 if platform.system() == 'Windows':
     _KILL_SIGNAL = signal.CTRL_BREAK_EVENT
@@ -173,9 +170,23 @@ def ci_env() -> bool:
     return _ci_env
 
 
+# choose randomly at import time
+_reg_addr: tuple[str, int] = (
+    '127.0.0.1',
+    random.randint(1000, 9999),
+)
+
+
 @pytest.fixture(scope='session')
-def arb_addr():
-    return _arb_addr
+def reg_addr() -> tuple[str, int]:
+
+    # globally override the runtime to the per-test-session-dynamic
+    # addr so that all tests never conflict with any other actor
+    # tree using the default.
+    from tractor import _root
+    _root._default_lo_addrs = [_reg_addr]
+
+    return _reg_addr
 
 
 def pytest_generate_tests(metafunc):
@@ -216,30 +227,35 @@ def sig_prog(proc, sig):
 def daemon(
     loglevel: str,
     testdir,
-    arb_addr: tuple[str, int],
+    reg_addr: tuple[str, int],
 ):
     '''
-    Run a daemon actor as a "remote arbiter".
+    Run a daemon root actor as a separate actor-process tree and
+    "remote registrar" for discovery-protocol related tests.
 
     '''
     if loglevel in ('trace', 'debug'):
-        # too much logging will lock up the subproc (smh)
-        loglevel = 'info'
+        # XXX: too much logging will lock up the subproc (smh)
+        loglevel: str = 'info'
 
-    cmdargs = [
-        sys.executable, '-c',
-        "import tractor; tractor.run_daemon([], registry_addr={}, loglevel={})"
-        .format(
-            arb_addr,
-            "'{}'".format(loglevel) if loglevel else None)
+    code: str = (
+            "import tractor; "
+            "tractor.run_daemon([], registry_addrs={reg_addrs}, loglevel={ll})"
+    ).format(
+        reg_addrs=str([reg_addr]),
+        ll="'{}'".format(loglevel) if loglevel else None,
+    )
+    cmd: list[str] = [
+        sys.executable,
+        '-c', code,
     ]
-    kwargs = dict()
+    kwargs = {}
     if platform.system() == 'Windows':
         # without this, tests hang on windows forever
         kwargs['creationflags'] = subprocess.CREATE_NEW_PROCESS_GROUP
 
     proc = testdir.popen(
-        cmdargs,
+        cmd,
         stdout=subprocess.PIPE,
         stderr=subprocess.PIPE,
         **kwargs,