diff --git a/.idea/dictionaries/ericf.xml b/.idea/dictionaries/ericf.xml
index 55028a7a..8b5ad5e0 100644
--- a/.idea/dictionaries/ericf.xml
+++ b/.idea/dictionaries/ericf.xml
@@ -1877,6 +1877,7 @@
       <w>recv</w>
       <w>redist</w>
       <w>redistributables</w>
+      <w>regtp</w>
       <w>relpath</w>
       <w>remainingchecks</w>
       <w>remoteapp</w>
diff --git a/ballisticacore-cmake/.idea/dictionaries/ericf.xml b/ballisticacore-cmake/.idea/dictionaries/ericf.xml
index 00f8f13b..e8d994ab 100644
--- a/ballisticacore-cmake/.idea/dictionaries/ericf.xml
+++ b/ballisticacore-cmake/.idea/dictionaries/ericf.xml
@@ -870,6 +870,7 @@
       <w>redundants</w>
       <w>refcounted</w>
       <w>refl</w>
+      <w>regtp</w>
       <w>rehel</w>
       <w>reloadmedia</w>
       <w>rendererdata</w>
diff --git a/tests/test_efro/test_message.py b/tests/test_efro/test_message.py
index 07ac208b..81161621 100644
--- a/tests/test_efro/test_message.py
+++ b/tests/test_efro/test_message.py
@@ -14,7 +14,7 @@ from efrotools.statictest import static_type_equals
 from efro.error import CleanError, RemoteError
 from efro.dataclassio import ioprepped
 from efro.message import (Message, Response, MessageProtocol, MessageSender,
-                          MessageReceiver, EmptyResponse)
+                          MessageReceiver)
 
 if TYPE_CHECKING:
     from typing import List, Type, Any, Callable, Union, Optional
@@ -176,9 +176,8 @@ TEST_PROTOCOL = MessageProtocol(
     response_types={
         0: _TResponse1,
         1: _TResponse2,
-        2: EmptyResponse,
     },
-    trusted_client=True,
+    trusted_sender=True,
     log_remote_exceptions=False,
 )
 
diff --git a/tools/efro/message.py b/tools/efro/message.py
index 99f619e1..3b59f78c 100644
--- a/tools/efro/message.py
+++ b/tools/efro/message.py
@@ -88,9 +88,13 @@ class MessageProtocol:
                  type_key: Optional[str] = None,
                  preserve_clean_errors: bool = True,
                  log_remote_exceptions: bool = True,
-                 trusted_client: bool = False) -> None:
+                 trusted_sender: bool = False) -> None:
         """Create a protocol with a given configuration.
 
+        Note that common response types are automatically registered
+        with (unchanging negative ids) so they don't need to be passed
+        explicitly (but can be if a different id is desired).
+
         If 'type_key' is provided, the message type ID is stored as the
         provided key in the message dict; otherwise it will be stored as
         part of a top level dict with the message payload appearing as a
@@ -100,10 +104,10 @@ class MessageProtocol:
         on the remote end will result in the same error raised locally.
         All other Exception types come across as efro.error.RemoteError.
 
-        If 'trusted_client' is True, stringified remote stack traces will
-        be included in the RemoteError. This should only be enabled in cases
-        where the client is trusted.
+        If 'trusted_sender' is True, stringified remote stack traces will
+        be included in the responses if errors occur.
         """
+        # pylint: disable=too-many-locals
         self.message_types_by_id: Dict[int, Type[Message]] = {}
         self.message_ids_by_type: Dict[Type[Message], int] = {}
         self.response_types_by_id: Dict[int, Type[Response]] = {}
@@ -129,12 +133,18 @@ class MessageProtocol:
             self.response_types_by_id[r_id] = r_type
             self.response_ids_by_type[r_type] = r_id
 
-        # If they didn't register ErrorResponse, do so with a special
-        # -1 id which ensures it will never conflict with user messages.
-        if ErrorResponse not in self.response_ids_by_type:
-            assert self.response_types_by_id.get(-1) is None
-            self.response_types_by_id[-1] = ErrorResponse
-            self.response_ids_by_type[ErrorResponse] = -1
+        # Go ahead and auto-register a few common response types
+        # if the user has not done so explicitly. Use unique IDs which
+        # will never change or overlap with user ids.
+        def _reg(reg_tp: Type[Response], reg_id: int) -> None:
+            if reg_tp in self.response_ids_by_type:
+                return
+            assert self.response_types_by_id.get(reg_id) is None
+            self.response_types_by_id[reg_id] = reg_tp
+            self.response_ids_by_type[reg_tp] = reg_id
+
+        _reg(ErrorResponse, -1)
+        _reg(EmptyResponse, -2)
 
         # Some extra-thorough validation in debug mode.
         if __debug__:
@@ -167,7 +177,7 @@ class MessageProtocol:
         self._type_key = type_key
         self.preserve_clean_errors = preserve_clean_errors
         self.log_remote_exceptions = log_remote_exceptions
-        self.trusted_client = trusted_client
+        self.trusted_sender = trusted_sender
 
     def encode_message(self, message: Message) -> bytes:
         """Encode a message to bytes for transport."""
@@ -671,7 +681,7 @@ class MessageReceiver:
 
                 err_response = ErrorResponse(
                     error_message=(traceback.format_exc()
-                                   if self._protocol.trusted_client else
+                                   if self._protocol.trusted_sender else
                                    'An unknown error has occurred.'),
                     error_type=ErrorType.OTHER)
             return self._protocol.encode_response(err_response)