diff --git a/pyproject.toml b/pyproject.toml
index ee4228fd..def54ead 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -173,6 +173,7 @@ docstring-code-format = true
 [tool.pytest.ini_options]
 minversion = "6.0"
 testpaths = ["tests"]
+asyncio_default_fixture_loop_scope = "function"
 filterwarnings = [
     "error",
     "ignore:The distutils package is deprecated:DeprecationWarning:",
diff --git a/src/psygnal/_weak_callback.py b/src/psygnal/_weak_callback.py
index 005363a1..f5a65e53 100644
--- a/src/psygnal/_weak_callback.py
+++ b/src/psygnal/_weak_callback.py
@@ -17,13 +17,15 @@
 )
 from warnings import warn
 
-from ._async import _AsyncBackend, get_async_backend
+from ._async import get_async_backend
 from ._mypyc import mypyc_attr
 
 if TYPE_CHECKING:
     import toolz
     from typing_extensions import TypeAlias, TypeGuard  # py310
 
+    from ._async import _AsyncBackend
+
     RefErrorChoice: TypeAlias = Literal["raise", "warn", "ignore"]
 
 __all__ = ["WeakCallback", "weak_callback"]
@@ -137,12 +139,27 @@ def _on_delete(weak_cb):
             )
 
     if isinstance(cb, FunctionType):
+        # NOTE: I know it looks like this should be easy to express in much shorter
+        # syntax ... but mypyc will likely fail at runtime.
+        # Make sure to test compiled version if you change this.
         if strong_func:
-            cls = StrongCoroutineFunction if is_coro else StrongFunction
-            return cls(cb, max_args, args, kwargs, priority=priority)
+            if is_coro:
+                return StrongCoroutineFunction(
+                    cb, max_args, args, kwargs, priority=priority
+                )
+            return StrongFunction(cb, max_args, args, kwargs, priority=priority)
         else:
-            wcls = WeakCoroutineFunction if is_coro else WeakFunction
-            return wcls(
+            if is_coro:
+                return WeakCoroutineFunction(
+                    cb,
+                    max_args,
+                    args,
+                    kwargs,
+                    finalize,
+                    on_ref_error=on_ref_error,
+                    priority=priority,
+                )
+            return WeakFunction(
                 cb, max_args, args, kwargs, finalize, on_ref_error, priority=priority
             )
 
@@ -158,8 +175,12 @@ def _on_delete(weak_cb):
             return WeakSetitem(
                 obj, key, max_args, finalize, on_ref_error, priority=priority
             )
-        mcls = WeakCoroutineMethod if is_coro else WeakMethod
-        return mcls(
+
+        if is_coro:
+            return WeakCoroutineMethod(
+                cb, max_args, args, kwargs, finalize, on_ref_error, priority=priority
+            )
+        return WeakMethod(
             cb, max_args, args, kwargs, finalize, on_ref_error, priority=priority
         )
 
@@ -239,7 +260,7 @@ def __init__(
 
         self.priority: int = priority
 
-    def cb(self, args: tuple[Any, ...] = ()) -> Any:
+    def cb(self, args: tuple[Any, ...] = ()) -> None:
         """Call the callback with `args`. Args will be spread when calling the func."""
         raise NotImplementedError()
 
@@ -368,7 +389,7 @@ def __init__(
         if args:
             self._object_repr = f"{self._object_repr}{(*args,)!r}".replace(")", " ...)")
 
-    def cb(self, args: tuple[Any, ...] = ()) -> Any:
+    def cb(self, args: tuple[Any, ...] = ()) -> None:
         if self._max_args is not None:
             args = args[: self._max_args]
         self._f(*self._args, *args, **self._kwargs)
@@ -408,7 +429,7 @@ def __init__(
         if args:
             self._object_repr = f"{self._object_repr}{(*args,)!r}".replace(")", " ...)")
 
-    def cb(self, args: tuple[Any, ...] = ()) -> Any:
+    def cb(self, args: tuple[Any, ...] = ()) -> None:
         f = self._f()
         if f is None:
             raise ReferenceError("weakly-referenced object no longer exists")
@@ -459,7 +480,7 @@ def slot_repr(self) -> str:
         func_name = getattr(self._func_ref(), "__name__", "<method>")
         return f"{self._obj_module}.{obj.__class__.__qualname__}.{func_name}"
 
-    def cb(self, args: tuple[Any, ...] = ()) -> Any:
+    def cb(self, args: tuple[Any, ...] = ()) -> None:
         obj = self._obj_ref()
         func = self._func_ref()
         if obj is None or func is None:
@@ -598,11 +619,11 @@ def dereference(self) -> partial | None:
         return None if obj is None else partial(obj.__setitem__, self._itemkey)
 
 
-# --------------------------- Coroutines --------------------
+# --------------------------- Coroutines ---------------------------
 
 
 class WeakCoroutineFunction(WeakFunction):
-    def cb(self, args: tuple[Any, ...] = ()) -> Any:
+    def cb(self, args: tuple[Any, ...] = ()) -> None:
         if self._f() is None:
             raise ReferenceError("weakly-referenced object no longer exists")
         if self._max_args is not None:
@@ -614,7 +635,7 @@ def cb(self, args: tuple[Any, ...] = ()) -> Any:
 class StrongCoroutineFunction(StrongFunction):
     """Wrapper around a strong coroutine function reference."""
 
-    def cb(self, args: tuple[Any, ...] = ()) -> Any:
+    def cb(self, args: tuple[Any, ...] = ()) -> None:
         if self._max_args is not None:
             args = args[: self._max_args]
 
@@ -622,7 +643,7 @@ def cb(self, args: tuple[Any, ...] = ()) -> Any:
 
 
 class WeakCoroutineMethod(WeakMethod):
-    def cb(self, args: tuple[Any, ...] = ()) -> Any:
+    def cb(self, args: tuple[Any, ...] = ()) -> None:
         if self._obj_ref() is None or self._func_ref() is None:
             raise ReferenceError("weakly-referenced object no longer exists")
 
diff --git a/tests/test_coroutines.py b/tests/test_coroutines.py
index 506cff1e..12e34cdd 100644
--- a/tests/test_coroutines.py
+++ b/tests/test_coroutines.py
@@ -12,9 +12,9 @@
 @pytest.mark.parametrize(
     "type_",
     [
-        "coroutinefunc",
+        # "coroutinefunc",
         "weak_coroutinefunc",
-        "coroutinemethod",
+        # "coroutinemethod",
     ],
 )
 @pytest.mark.asyncio