diff --git a/ormar/decorators/signals.py b/ormar/decorators/signals.py
index 468fc0c..54e97e5 100644
--- a/ormar/decorators/signals.py
+++ b/ormar/decorators/signals.py
@@ -1,4 +1,4 @@
-from typing import Callable, List, TYPE_CHECKING, Type, Union
+from typing import Callable, List, Type, TYPE_CHECKING, Union
 
 if TYPE_CHECKING:  # pragma: no cover
     from ormar import Model
diff --git a/ormar/signals/signal.py b/ormar/signals/signal.py
index e2c5275..d5b4a5c 100644
--- a/ormar/signals/signal.py
+++ b/ormar/signals/signal.py
@@ -1,6 +1,6 @@
 import asyncio
 import inspect
-from typing import Any, Callable, Dict, List, TYPE_CHECKING, Tuple, Type, Union
+from typing import Any, Callable, Dict, Tuple, Type, TYPE_CHECKING, Union
 
 from ormar.exceptions import SignalDefinitionError
 
@@ -45,7 +45,7 @@ class Signal:
     """
 
     def __init__(self) -> None:
-        self._receivers: List[Tuple[Union[int, Tuple[int, int]], Callable]] = []
+        self._receivers: Dict[Union[int, Tuple[int, int]], Callable] = {}
 
     def connect(self, receiver: Callable) -> None:
         """
@@ -63,8 +63,8 @@ class Signal:
                 "Signal receivers must accept **kwargs argument."
             )
         new_receiver_key = make_id(receiver)
-        if not any(rec_id == new_receiver_key for rec_id, _ in self._receivers):
-            self._receivers.append((new_receiver_key, receiver))
+        if new_receiver_key not in self._receivers:
+            self._receivers[new_receiver_key] = receiver
 
     def disconnect(self, receiver: Callable) -> bool:
         """
@@ -75,15 +75,10 @@ class Signal:
         :return: flag if receiver was removed
         :rtype: bool
         """
-        removed = False
         new_receiver_key = make_id(receiver)
-        for ind, rec in enumerate(self._receivers):
-            rec_id, _ = rec
-            if rec_id == new_receiver_key:
-                removed = True
-                del self._receivers[ind]
-                break
-        return removed
+        receiver_func: Union[Callable, None] = self._receivers.pop(
+            new_receiver_key, None)
+        return True if receiver_func is not None else False
 
     async def send(self, sender: Type["Model"], **kwargs: Any) -> None:
         """
@@ -93,28 +88,22 @@ class Signal:
         :param kwargs: arguments passed to receivers
         :type kwargs: Any
         """
-        receivers = []
-        for receiver in self._receivers:
-            _, receiver_func = receiver
-            receivers.append(receiver_func(sender=sender, **kwargs))
+        receivers = [
+            receiver_func(sender=sender, **kwargs)
+            for receiver_func in self._receivers.values()
+        ]
         await asyncio.gather(*receivers)
 
 
-class SignalEmitter:
+class SignalEmitter(dict):
     """
     Emitter that registers the signals in internal dictionary.
     If signal with given name does not exist it's auto added on access.
     """
-
-    if TYPE_CHECKING:  # pragma: no cover
-        signals: Dict[str, Signal]
-
-    def __init__(self) -> None:
-        object.__setattr__(self, "signals", dict())
-
     def __getattr__(self, item: str) -> Signal:
-        return self.signals.setdefault(item, Signal())
+        return self.setdefault(item, Signal())
 
-    def __setattr__(self, key: str, value: Any) -> None:
-        signals = object.__getattribute__(self, "signals")
-        signals[key] = value
+    def __setattr__(self, key: str, value: Signal) -> None:
+        if not isinstance(value, Signal):
+            raise SignalDefinitionError(f"{value} is not valid signal")
+        self[key] = value
diff --git a/tests/test_signals/test_signals.py b/tests/test_signals/test_signals.py
index 4832682..3dbcfa6 100644
--- a/tests/test_signals/test_signals.py
+++ b/tests/test_signals/test_signals.py
@@ -7,6 +7,7 @@ import sqlalchemy
 
 import ormar
 from ormar import post_delete, post_save, post_update, pre_delete, pre_save, pre_update
+from ormar.signals import SignalEmitter
 from ormar.exceptions import SignalDefinitionError
 from tests.settings import DATABASE_URL
 
@@ -77,6 +78,12 @@ def test_passing_callable_without_kwargs():
             pass
 
 
+def test_invalid_signal():
+    emitter = SignalEmitter()
+    with pytest.raises(SignalDefinitionError):
+        emitter.save = 1
+
+
 @pytest.mark.asyncio
 async def test_signal_functions(cleanup):
     async with database: