diff --git a/src/easynetwork/lowlevel/api_async/backend/_asyncio/backend.py b/src/easynetwork/lowlevel/api_async/backend/_asyncio/backend.py
index a48b2356..68fa4d51 100644
--- a/src/easynetwork/lowlevel/api_async/backend/_asyncio/backend.py
+++ b/src/easynetwork/lowlevel/api_async/backend/_asyncio/backend.py
@@ -281,10 +281,13 @@ def create_event(self) -> IEvent:
         return self.__asyncio.Event()
 
     def create_condition_var(self, lock: ILock | None = None) -> ICondition:
-        if lock is not None:
-            assert isinstance(lock, self.__asyncio.Lock)  # nosec assert_used
-
-        return self.__asyncio.Condition(lock)
+        match lock:
+            case None:
+                return self.__asyncio.Condition()
+            case self.__asyncio.Lock():
+                return self.__asyncio.Condition(lock)
+            case _:
+                raise TypeError("lock must be a asyncio.Lock")
 
     async def run_in_thread(
         self,
diff --git a/src/easynetwork/lowlevel/api_async/backend/_trio/backend.py b/src/easynetwork/lowlevel/api_async/backend/_trio/backend.py
index 166a946d..bfa4fa95 100644
--- a/src/easynetwork/lowlevel/api_async/backend/_trio/backend.py
+++ b/src/easynetwork/lowlevel/api_async/backend/_trio/backend.py
@@ -260,10 +260,13 @@ def create_event(self) -> IEvent:
         return self.__trio.Event()
 
     def create_condition_var(self, lock: ILock | None = None) -> ICondition:
-        if lock is not None:
-            assert isinstance(lock, self.__trio.Lock)  # nosec assert_used
-
-        return self.__trio.Condition(lock)
+        match lock:
+            case None:
+                return self.__trio.Condition()
+            case self.__trio.Lock():
+                return self.__trio.Condition(lock)
+            case _:
+                raise TypeError("lock must be a trio.Lock")
 
     async def run_in_thread(
         self,
diff --git a/src/easynetwork/lowlevel/api_async/backend/abc.py b/src/easynetwork/lowlevel/api_async/backend/abc.py
index 79974cb6..3c5eadef 100644
--- a/src/easynetwork/lowlevel/api_async/backend/abc.py
+++ b/src/easynetwork/lowlevel/api_async/backend/abc.py
@@ -1175,8 +1175,23 @@ def create_condition_var(self, lock: ILock | None = ...) -> ICondition:
         """
         Creates a Condition variable object for inter-task synchronization.
 
+        If `lock` is given and not :data:`None`, it should be a lock created by :meth:`create_lock`.
+        While it is guaranteed to work with a lock from :meth:`create_lock`, it can be any other implementation
+        (such as the lock returned by :meth:`create_fair_lock`), but it can also refuse other implementations.
+
+        Generic code should expect the function to fail::
+
+            try:
+                cond = backend.create_condition_var(backend.create_fair_lock())
+            except TypeError:
+                # Cannot use a fair lock. Use the default implementation instead.
+                cond = backend.create_condition_var()
+
         Parameters:
-            lock: If given, it must be a lock created by :meth:`create_lock`. Otherwise a new Lock object is created automatically.
+            lock: The lock instance to use under the hood.
+
+        Raises:
+            TypeError: `lock` type is not supported.
 
         Returns:
             A new Condition.
diff --git a/tests/unit_test/test_async/test_asyncio_backend/test_backend.py b/tests/unit_test/test_async/test_asyncio_backend/test_backend.py
index 1ea45716..280eb66e 100644
--- a/tests/unit_test/test_async/test_asyncio_backend/test_backend.py
+++ b/tests/unit_test/test_async/test_asyncio_backend/test_backend.py
@@ -11,6 +11,7 @@
 from easynetwork.lowlevel.api_async.backend._asyncio.dns_resolver import AsyncIODNSResolver
 from easynetwork.lowlevel.api_async.backend._asyncio.stream.listener import AbstractAcceptedSocketFactory, AcceptedSocketFactory
 from easynetwork.lowlevel.api_async.backend._asyncio.stream.socket import StreamReaderBufferedProtocol
+from easynetwork.lowlevel.api_async.backend.abc import ILock
 
 import pytest
 
@@ -805,9 +806,28 @@ async def test____create_condition_var____use_asyncio_Condition_class(
         condition = backend.create_condition_var(mock_lock)
 
         # Assert
-        mock_Condition.assert_called_once_with(mock_lock)
+        if mock_lock is None:
+            mock_Condition.assert_called_once_with()
+        else:
+            mock_Condition.assert_called_once_with(mock_lock)
         assert condition is mocker.sentinel.condition_var
 
+    async def test____create_condition_var____invalid_Lock_type(
+        self,
+        backend: AsyncIOBackend,
+        mocker: MockerFixture,
+    ) -> None:
+        # Arrange
+        mock_lock: MagicMock = mocker.NonCallableMagicMock(spec=ILock)
+        mock_Condition = mocker.patch("asyncio.Condition", return_value=mocker.sentinel.condition_var)
+
+        # Act
+        with pytest.raises(TypeError, match=r"^lock must be a asyncio\.Lock$"):
+            _ = backend.create_condition_var(mock_lock)
+
+        # Assert
+        mock_Condition.assert_not_called()
+
     @pytest.mark.parametrize("abandon_on_cancel", [False, True], ids=lambda p: f"abandon_on_cancel=={p}")
     async def test____run_in_thread____use_loop_run_in_executor(
         self,
diff --git a/tests/unit_test/test_async/test_trio_backend/test_backend.py b/tests/unit_test/test_async/test_trio_backend/test_backend.py
index 959b734d..cb82b952 100644
--- a/tests/unit_test/test_async/test_trio_backend/test_backend.py
+++ b/tests/unit_test/test_async/test_trio_backend/test_backend.py
@@ -5,6 +5,7 @@
 from typing import TYPE_CHECKING, Any, Final
 
 from easynetwork.lowlevel.api_async.backend._trio.backend import TrioBackend
+from easynetwork.lowlevel.api_async.backend.abc import ILock
 
 import pytest
 
@@ -675,9 +676,28 @@ async def test____create_condition_var____use_trio_Condition_class(
         condition = backend.create_condition_var(mock_lock)
 
         # Assert
-        mock_Condition.assert_called_once_with(mock_lock)
+        if mock_lock is None:
+            mock_Condition.assert_called_once_with()
+        else:
+            mock_Condition.assert_called_once_with(mock_lock)
         assert condition is mocker.sentinel.condition_var
 
+    async def test____create_condition_var____invalid_Lock_type(
+        self,
+        backend: TrioBackend,
+        mocker: MockerFixture,
+    ) -> None:
+        # Arrange
+        mock_lock: MagicMock = mocker.NonCallableMagicMock(spec=ILock)
+        mock_Condition = mocker.patch("trio.Condition", return_value=mocker.sentinel.condition_var)
+
+        # Act
+        with pytest.raises(TypeError, match=r"^lock must be a trio\.Lock$"):
+            _ = backend.create_condition_var(mock_lock)
+
+        # Assert
+        mock_Condition.assert_not_called()
+
     @pytest.mark.parametrize("abandon_on_cancel", [False, True], ids=lambda p: f"abandon_on_cancel=={p}")
     async def test____run_in_thread____use_loop_run_in_executor(
         self,