diff --git a/fast_depends/use.py b/fast_depends/use.py
index 972a9c6..0e88ede 100644
--- a/fast_depends/use.py
+++ b/fast_depends/use.py
@@ -184,7 +184,7 @@ def injected_wrapper(*args: P.args, **kwargs: P.kwargs) -> T:
 
 
 class solve_async_gen:
-    _iter: Optional[AsyncIterator[Any]]
+    _iter: Optional[AsyncIterator[Any]] = None
 
     def __init__(
         self,
@@ -231,7 +231,7 @@ async def __anext__(self) -> Any:
 
 
 class solve_gen:
-    _iter: Optional[Iterator[Any]]
+    _iter: Optional[Iterator[Any]] = None
 
     def __init__(
         self,
diff --git a/tests/async/test_depends.py b/tests/async/test_depends.py
index 592436b..ebb0d2b 100644
--- a/tests/async/test_depends.py
+++ b/tests/async/test_depends.py
@@ -1,4 +1,5 @@
 import logging
+from contextlib import asynccontextmanager
 from dataclasses import dataclass
 from functools import partial
 from unittest.mock import Mock
@@ -469,3 +470,17 @@ async def func(a=Depends(dep)):
         return a
 
     assert await func() == "a"
+
+
+@pytest.mark.anyio
+async def test_asynccontextmanager():
+    async def dep(a: str = "a"):
+        return a
+
+    @asynccontextmanager
+    @inject
+    async def func(a: str, b: str = Depends(dep)):
+        yield a == b
+
+    async with func("a") as is_equal:
+        assert is_equal
diff --git a/tests/sync/test_depends.py b/tests/sync/test_depends.py
index ef56dfc..3071a5a 100644
--- a/tests/sync/test_depends.py
+++ b/tests/sync/test_depends.py
@@ -1,4 +1,5 @@
 import logging
+from contextlib import contextmanager
 from dataclasses import dataclass
 from functools import partial
 from unittest.mock import Mock
@@ -352,3 +353,16 @@ def func(a=Depends(dep)):
         return a
 
     assert func() == "a"
+
+
+def test_contextmanager():
+    def dep(a: str = "a"):
+        return a
+
+    @contextmanager
+    @inject
+    def func(a: str, b: str = Depends(dep)):
+        yield a == b
+
+    with func("a") as is_equal:
+        assert is_equal