diff --git a/labgrid/remote/client.py b/labgrid/remote/client.py
index 731e81950..5ab4f0683 100755
--- a/labgrid/remote/client.py
+++ b/labgrid/remote/client.py
@@ -23,6 +23,7 @@
 from collections import defaultdict, OrderedDict
 from datetime import datetime
 from pprint import pformat
+from typing import Any, Dict
 
 import attr
 import grpc
@@ -1566,7 +1567,19 @@ def ensure_event_loop(external_loop=None):
     return loop
 
 
-def start_session(address, extra=None, debug=False, loop=None):
+def start_session(
+    address: str, *, extra: Dict[str, Any] = None, debug: bool = False, loop: "asyncio.AbstractEventLoop | None" = None
+):
+    """
+    Starts a ClientSession.
+
+    Args:
+        address: coordinator address as HOST[:PORT], PORT defaults to 20408
+        extra: additional kwargs for ClientSession
+        debug: set debug mode of the event loop
+        loop: explicit event loop to use (otherwise a previously stashed loop,
+              if retrievable the current thread's loop or a new loop is used)
+    """
     loop = ensure_event_loop(loop)
 
     if extra is None:
diff --git a/labgrid/resource/remote.py b/labgrid/resource/remote.py
index 1b8256ef0..b8adb2524 100644
--- a/labgrid/resource/remote.py
+++ b/labgrid/resource/remote.py
@@ -22,7 +22,7 @@ def _start(self):
 
         from ..remote.client import start_session
         try:
-            self.session = start_session(self.url, {'env': self.env})
+            self.session = start_session(self.url, extra={'env': self.env})
         except ConnectionRefusedError as e:
             raise ConnectionRefusedError(f"Could not connect to coordinator {self.url}") \
                 from e