diff --git a/lib/tfw/builtins/event_handler.py b/lib/tfw/builtins/event_handler.py
index 1732044..9696fe4 100644
--- a/lib/tfw/builtins/event_handler.py
+++ b/lib/tfw/builtins/event_handler.py
@@ -1,10 +1,9 @@
 from tfw.event_handlers import EventHandlerBase
-from tfw.networking import Scope
 
 from .tfw_server_connector import TFWServerConnector
 
 
 class EventHandler(EventHandlerBase):
     # pylint: disable=abstract-method
-    def __init__(self, key, scope=Scope.ZMQ):
-        super().__init__(key, TFWServerConnector(), scope=scope)
+    def _build_server_connector(self):
+        return TFWServerConnector()
diff --git a/lib/tfw/builtins/fsm_aware_event_handler.py b/lib/tfw/builtins/fsm_aware_event_handler.py
index a619ca1..d585651 100644
--- a/lib/tfw/builtins/fsm_aware_event_handler.py
+++ b/lib/tfw/builtins/fsm_aware_event_handler.py
@@ -1,12 +1,10 @@
-from abc import ABC
-
 from tfw.components import FSMAware
 from tfw.networking import Scope
 
 from .event_handler import EventHandler
 
 
-class FSMAwareEventHandler(EventHandler, FSMAware, ABC):
+class FSMAwareEventHandler(EventHandler, FSMAware):
     # pylint: disable=abstract-method
     """
     Abstract base class for EventHandlers which automatically
diff --git a/lib/tfw/builtins/tfw_server_connector.py b/lib/tfw/builtins/tfw_server_connector.py
index 161a6cb..8b8b7c3 100644
--- a/lib/tfw/builtins/tfw_server_connector.py
+++ b/lib/tfw/builtins/tfw_server_connector.py
@@ -1,19 +1,25 @@
-from functools import partial
-
 from tfw.networking import ServerUplinkConnector, ServerConnector
 from tfw.config import TFWENV
 
 
-UPLINK_CONN_ADDR = f'tcp://localhost:{TFWENV.PULL_PORT}'
-DOWNLINK_CONN_ADDR = f'tcp://localhost:{TFWENV.PUB_PORT}'
+class ConnAddrMixin:
+    @property
+    def uplink_conn_addr(self):
+        return f'tcp://localhost:{TFWENV.PULL_PORT}'
+
+    @property
+    def downlink_conn_addr(self):
+        return f'tcp://localhost:{TFWENV.PUB_PORT}'
 
 
-TFWServerUplinkConnector = partial(
-    ServerUplinkConnector,
-    connect_addr=UPLINK_CONN_ADDR
-)
-TFWServerConnector = partial(
-    ServerConnector,
-    downlink_connect_addr=DOWNLINK_CONN_ADDR,
-    uplink_connect_addr=UPLINK_CONN_ADDR
-)
+class TFWServerUplinkConnector(ServerUplinkConnector, ConnAddrMixin):
+    def __init__(self):
+        super().__init__(self.uplink_conn_addr)
+
+
+class TFWServerConnector(ServerConnector, ConnAddrMixin):
+    def __init__(self):
+        super().__init__(
+            self.downlink_conn_addr,
+            self.uplink_conn_addr
+        )
diff --git a/lib/tfw/event_handlers/event_handler_base.py b/lib/tfw/event_handlers/event_handler_base.py
index 051363e..b87606f 100644
--- a/lib/tfw/event_handlers/event_handler_base.py
+++ b/lib/tfw/event_handlers/event_handler_base.py
@@ -1,10 +1,13 @@
 import logging
+from abc import ABC, abstractmethod
 from typing import Iterable
 
+from tfw.networking import Scope
+
 LOG = logging.getLogger(__name__)
 
 
-class EventHandlerBase:
+class EventHandlerBase(ABC):
     """
     Abstract base class for all Python based EventHandlers. Useful implementation template
     for other languages.
@@ -13,9 +16,9 @@ class EventHandlerBase:
     """
     _instances = set()
 
-    def __init__(self, key, server_connector, scope):
+    def __init__(self, key, scope=Scope.ZMQ):
         type(self)._instances.add(self)
-        self.server_connector = server_connector
+        self.server_connector = self._build_server_connector()
         self.scope = scope
         self.keys = []
         if isinstance(key, str):
@@ -26,6 +29,10 @@ class EventHandlerBase:
         self.subscribe(*self.keys)
         self.server_connector.register_callback(self.event_handler_callback)
 
+    @abstractmethod
+    def _build_server_connector(self):
+        raise NotImplementedError()
+
     def subscribe(self, *keys):
         """
         Subscribe this EventHandler to receive events for given keys.