diff --git a/tractor/__init__.py b/tractor/__init__.py
index 0667bd5..d8d6489 100644
--- a/tractor/__init__.py
+++ b/tractor/__init__.py
@@ -17,7 +17,7 @@ from ._actor import (
 )
 from ._trionics import open_nursery
 from ._state import current_actor
-from ._exceptions import RemoteActorError
+from ._exceptions import RemoteActorError, ModuleNotExposed
 
 
 __all__ = [
@@ -29,6 +29,7 @@ __all__ = [
     'Channel',
     'MultiError',
     'RemoteActorError',
+    'ModuleNotExposed',
 ]
 
 
diff --git a/tractor/_actor.py b/tractor/_actor.py
index 750487a..d9a5ee1 100644
--- a/tractor/_actor.py
+++ b/tractor/_actor.py
@@ -15,7 +15,7 @@ from async_generator import asynccontextmanager, aclosing
 
 from ._ipc import Channel, _connect_chan
 from .log import get_console_log, get_logger
-from ._exceptions import pack_error, InternalActorError
+from ._exceptions import pack_error, InternalActorError, ModuleNotExposed
 from ._portal import (
     Portal,
     open_portal,
@@ -236,6 +236,12 @@ class Actor:
             #     self._mods.pop('test_discovery')
             # TODO: how to test the above?
 
+    def _get_rpc_func(self, ns, funcname):
+        try:
+            return getattr(self._mods[ns], funcname)
+        except KeyError as err:
+            raise ModuleNotExposed(*err.args)
+
     async def _stream_handler(
         self,
         stream: trio.SocketStream,
@@ -398,7 +404,14 @@ class Actor:
                 if ns == 'self':
                     func = getattr(self, funcname)
                 else:
-                    func = getattr(self._mods[ns], funcname)
+                    # complain to client about restricted modules
+                    try:
+                        func = self._get_rpc_func(ns, funcname)
+                    except (ModuleNotExposed, AttributeError) as err:
+                        err_msg = pack_error(err)
+                        err_msg['cid'] = cid
+                        await chan.send(err_msg)
+                        continue
 
                 # spin up a task for the requested function
                 log.debug(f"Spawning task for {func}")
diff --git a/tractor/_exceptions.py b/tractor/_exceptions.py
index 7244396..efedcf0 100644
--- a/tractor/_exceptions.py
+++ b/tractor/_exceptions.py
@@ -1,16 +1,28 @@
 """
 Our classy exception set.
 """
+import importlib
 import builtins
 import traceback
 
 
+_this_mod = importlib.import_module(__name__)
+
+
 class RemoteActorError(Exception):
     # TODO: local recontruction of remote exception deats
     "Remote actor exception bundled locally"
     def __init__(self, message, type_str, **msgdata):
         super().__init__(message)
-        self.type = getattr(builtins, type_str, Exception)
+        for ns in [builtins, _this_mod]:
+            try:
+                self.type = getattr(ns, type_str)
+                break
+            except AttributeError:
+                continue
+        else:
+            self.type = Exception
+
         self.msgdata = msgdata
 
     # TODO: a trio.MultiError.catch like context manager
@@ -27,6 +39,10 @@ class NoResult(RuntimeError):
     "No final result is expected for this actor"
 
 
+class ModuleNotExposed(RuntimeError):
+    "The requested module is not exposed for RPC"
+
+
 def pack_error(exc):
     """Create an "error message" for tranmission over
     a channel (aka the wire).