diff --git a/asynq/batching.py b/asynq/batching.py
index 25d76fe..1bb448a 100644
--- a/asynq/batching.py
+++ b/asynq/batching.py
@@ -20,7 +20,6 @@
 from . import _debug
 from . import profiler
 
-
 __traceback_hide__ = True
 
 _debug_options = _debug.options
diff --git a/asynq/decorators.py b/asynq/decorators.py
index 5961f0d..5adaf9e 100644
--- a/asynq/decorators.py
+++ b/asynq/decorators.py
@@ -15,7 +15,9 @@
 
 import asyncio
 import inspect
-from typing import Any, Coroutine
+import logging
+from collections.abc import Coroutine
+from typing import Any
 
 import qcore.decorators
 import qcore.helpers as core_helpers
@@ -25,6 +27,7 @@
 from .asynq_to_async import AsyncioMode, is_asyncio_mode, resolve_awaitables
 
 __traceback_hide__ = True
+logger = logging.getLogger("asynq")
 
 
 def lazy(fn):
@@ -147,12 +150,13 @@ def is_pure_async_fn(self):
 class PureAsyncDecorator(qcore.decorators.DecoratorBase):
     binder_cls = PureAsyncDecoratorBinder
 
-    def __init__(self, fn, task_cls, kwargs={}, asyncio_fn=None):
+    def __init__(self, fn, task_cls, kwargs={}, asyncio_fn=None, allow_sync_call=False):
         qcore.decorators.DecoratorBase.__init__(self, fn)
         self.task_cls = task_cls
         self.needs_wrapper = core_inspection.is_cython_or_generator(fn)
         self.kwargs = kwargs
         self.asyncio_fn = asyncio_fn
+        self.allow_sync_call = allow_sync_call
 
     def name(self):
         return "@asynq(pure=True)"
@@ -202,8 +206,8 @@ def asyncio(self, *args, **kwargs) -> Coroutine[Any, Any, Any]:
 class AsyncDecorator(PureAsyncDecorator):
     binder_cls = AsyncDecoratorBinder
 
-    def __init__(self, fn, cls, kwargs={}, asyncio_fn=None):
-        super().__init__(fn, cls, kwargs, asyncio_fn)
+    def __init__(self, fn, cls, kwargs={}, asyncio_fn=None, allow_sync_call=False):
+        super().__init__(fn, cls, kwargs, asyncio_fn, allow_sync_call)
 
     def is_pure_async_fn(self):
         return False
@@ -216,9 +220,16 @@ def name(self):
 
     def __call__(self, *args, **kwargs):
         if is_asyncio_mode():
-            raise RuntimeError("asyncio mode does not support synchronous calls")
-
-        return self._call_pure(args, kwargs).value()
+            if self.allow_sync_call:
+                logger.warning(
+                    f"asyncio mode does not support synchronous calls: {self.fn.__name__} at {inspect.getsourcefile(self.fn)}"
+                )
+            else:
+                raise RuntimeError(
+                    f"asyncio mode does not support synchronous calls: {self.fn.__name__} at {inspect.getsourcefile(self.fn)}"
+                )
+        else:
+            return self._call_pure(args, kwargs).value()
 
 
 class AsyncAndSyncPairDecoratorBinder(AsyncDecoratorBinder):
@@ -232,14 +243,24 @@ def __call__(self, *args, **kwargs):
 class AsyncAndSyncPairDecorator(AsyncDecorator):
     binder_cls = AsyncAndSyncPairDecoratorBinder
 
-    def __init__(self, fn, cls, sync_fn, kwargs={}, asyncio_fn=None):
-        AsyncDecorator.__init__(self, fn, cls, kwargs, asyncio_fn)
+    def __init__(
+        self, fn, cls, sync_fn, kwargs={}, asyncio_fn=None, allow_sync_call=False
+    ):
+        AsyncDecorator.__init__(self, fn, cls, kwargs, asyncio_fn, allow_sync_call)
         self.sync_fn = sync_fn
 
     def __call__(self, *args, **kwargs):
         if is_asyncio_mode():
-            raise RuntimeError("asyncio mode does not support synchronous calls")
-        return self.sync_fn(*args, **kwargs)
+            if self.allow_sync_call:
+                logger.warning(
+                    f"asyncio mode does not support synchronous calls: {self.fn.__name__} at {inspect.getsourcefile(self.fn)}"
+                )
+            else:
+                raise RuntimeError(
+                    f"asyncio mode does not support synchronous calls: {self.fn.__name__} at {inspect.getsourcefile(self.fn)}"
+                )
+        else:
+            return self.sync_fn(*args, **kwargs)
 
     def __get__(self, owner, cls):
         # This is needed so that we can use objects with __get__ as the sync_fn. If we just rely on
@@ -262,9 +283,11 @@ def __get__(self, owner, cls):
 
 
 class AsyncProxyDecorator(AsyncDecorator):
-    def __init__(self, fn, asyncio_fn=None):
+    def __init__(self, fn, asyncio_fn=None, allow_sync_call=False):
         # we don't need the task class but still need to pass it to the superclass
-        AsyncDecorator.__init__(self, fn, None, asyncio_fn=asyncio_fn)
+        AsyncDecorator.__init__(
+            self, fn, None, asyncio_fn=asyncio_fn, allow_sync_call=allow_sync_call
+        )
 
     def asyncio(self, *args, **kwargs) -> Coroutine[Any, Any, Any]:
         if self.asyncio_fn is None:
@@ -288,8 +311,10 @@ def _call_pure(self, args, kwargs):
 
 
 class AsyncAndSyncPairProxyDecorator(AsyncProxyDecorator):
-    def __init__(self, fn, sync_fn, asyncio_fn=None):
-        AsyncProxyDecorator.__init__(self, fn, asyncio_fn=asyncio_fn)
+    def __init__(self, fn, sync_fn, asyncio_fn=None, allow_sync_call=False):
+        AsyncProxyDecorator.__init__(
+            self, fn, asyncio_fn=asyncio_fn, allow_sync_call=allow_sync_call
+        )
         self.sync_fn = sync_fn
 
     def __call__(self, *args, **kwargs):
@@ -297,7 +322,12 @@ def __call__(self, *args, **kwargs):
 
 
 def asynq(
-    pure=False, sync_fn=None, cls=async_task.AsyncTask, asyncio_fn=None, **kwargs
+    pure=False,
+    sync_fn=None,
+    cls=async_task.AsyncTask,
+    asyncio_fn=None,
+    allow_sync_call=False,
+    **kwargs,
 ):
     """Async task decorator.
     Converts a method returning generator object to
@@ -317,18 +347,23 @@ def decorate(fn):
             return qcore.decorators.decorate(PureAsyncDecorator, cls, kwargs)(fn)
         elif sync_fn is None:
             decorated = qcore.decorators.decorate(
-                AsyncDecorator, cls, kwargs, asyncio_fn
+                AsyncDecorator, cls, kwargs, asyncio_fn, allow_sync_call
             )(fn)
             return decorated
         else:
             return qcore.decorators.decorate(
-                AsyncAndSyncPairDecorator, cls, sync_fn, kwargs, asyncio_fn
+                AsyncAndSyncPairDecorator,
+                cls,
+                sync_fn,
+                kwargs,
+                asyncio_fn,
+                allow_sync_call,
             )(fn)
 
     return decorate
 
 
-def async_proxy(pure=False, sync_fn=None, asyncio_fn=None):
+def async_proxy(pure=False, sync_fn=None, asyncio_fn=None, allow_sync_call=False):
     if sync_fn is not None:
         assert pure is False, "sync_fn=? cannot be used together with pure=True"
 
@@ -339,7 +374,7 @@ def decorate(fn):
             return qcore.decorators.decorate(AsyncProxyDecorator, asyncio_fn)(fn)
         else:
             return qcore.decorators.decorate(
-                AsyncAndSyncPairProxyDecorator, sync_fn, asyncio_fn
+                AsyncAndSyncPairProxyDecorator, sync_fn, asyncio_fn, allow_sync_call
             )(fn)
 
     return decorate
diff --git a/asynq/decorators.pyi b/asynq/decorators.pyi
index bbf7dfb..c9d9ecd 100644
--- a/asynq/decorators.pyi
+++ b/asynq/decorators.pyi
@@ -46,6 +46,7 @@ class PureAsyncDecorator(qcore.decorators.DecoratorBase, Generic[_T, _P]):
         task_cls: Optional[type[futures.FutureBase]],
         kwargs: Mapping[str, Any] = ...,
         asyncio_fn: Optional[Callable[_P, Coroutine[Any, Any, _T]]] = ...,
+        allow_sync_call: bool = ...,
     ) -> None: ...
     @overload
     def __init__(
@@ -54,6 +55,7 @@ class PureAsyncDecorator(qcore.decorators.DecoratorBase, Generic[_T, _P]):
         task_cls: Optional[type[futures.FutureBase]],
         kwargs: Mapping[str, Any] = ...,
         asyncio_fn: Optional[Callable[_P, Coroutine[Any, Any, _T]]] = ...,
+        allow_sync_call: bool = ...,
     ) -> None: ...
     def name(self) -> str: ...
     def is_pure_async_fn(self) -> bool: ...
@@ -84,6 +86,7 @@ class AsyncDecorator(PureAsyncDecorator[_T, _P]):
         cls: Optional[type[futures.FutureBase]],
         kwargs: Mapping[str, Any] = ...,
         asyncio_fn: Optional[Callable[_P, Coroutine[Any, Any, _T]]] = ...,
+        allow_sync_call: bool = ...,
     ): ...
     @overload
     def __init__(
@@ -92,6 +95,7 @@ class AsyncDecorator(PureAsyncDecorator[_T, _P]):
         cls: Optional[type[futures.FutureBase]],
         kwargs: Mapping[str, Any] = ...,
         asyncio_fn: Optional[Callable[_P, Coroutine[Any, Any, _T]]] = ...,
+        allow_sync_call: bool = ...,
     ): ...
     def is_pure_async_fn(self) -> bool: ...
     def asynq(self, *args: Any, **kwargs: Any) -> async_task.AsyncTask[_T]: ...
@@ -117,6 +121,7 @@ class AsyncProxyDecorator(AsyncDecorator[_T, _P]):
         self,
         fn: Callable[..., futures.FutureBase[_T]],
         asyncio_fn: Optional[Callable[..., Coroutine[Any, Any, _T]]] = ...,
+        allow_sync_call: bool = ...,
     ) -> None: ...
 
 class AsyncAndSyncPairProxyDecorator(AsyncProxyDecorator[_T, _P]):
@@ -125,6 +130,7 @@ class AsyncAndSyncPairProxyDecorator(AsyncProxyDecorator[_T, _P]):
         fn: Callable[..., futures.FutureBase[_T]],
         sync_fn: Callable[..., _T],
         asyncio_fn: Optional[Callable[..., Coroutine[Any, Any, _T]]] = ...,
+        allow_sync_call: bool = ...,
     ) -> None: ...
     def __call__(self, *args: Any, **kwargs: Any) -> _T: ...
 
@@ -142,6 +148,7 @@ def asynq(
     sync_fn: Optional[Callable[_P, _T]] = ...,
     cls: type[futures.FutureBase] = ...,
     asyncio_fn: Optional[Callable[_P, Coroutine[Any, Any, _T]]] = ...,
+    allow_sync_call: bool = ...,
     **kwargs: Any,
 ) -> _MkAsyncDecorator: ...
 @overload
@@ -151,6 +158,7 @@ def asynq(
     sync_fn: Optional[Callable[_P, _T]] = ...,
     cls: type[futures.FutureBase] = ...,
     asyncio_fn: Optional[Callable[_P, Coroutine[Any, Any, _T]]] = ...,
+    allow_sync_call: bool = ...,
     **kwargs: Any,
 ) -> _MkPureAsyncDecorator: ...
 @overload
diff --git a/asynq/futures.py b/asynq/futures.py
index 7b5cccd..a45454f 100644
--- a/asynq/futures.py
+++ b/asynq/futures.py
@@ -21,7 +21,6 @@
 from . import debug
 from . import _debug
 
-
 __traceback_hide__ = True
 
 
diff --git a/asynq/scoped_value.py b/asynq/scoped_value.py
index f8eb332..bac7e25 100644
--- a/asynq/scoped_value.py
+++ b/asynq/scoped_value.py
@@ -28,7 +28,6 @@
 
 from . import contexts
 
-
 _empty_context = qcore.empty_context
 
 
diff --git a/asynq/tests/debug_cache.py b/asynq/tests/debug_cache.py
index c6a32c7..9da4ab6 100644
--- a/asynq/tests/debug_cache.py
+++ b/asynq/tests/debug_cache.py
@@ -16,7 +16,6 @@
 from asynq import scheduler
 from .caching import ExternalCacheBase, LocalCache
 
-
 # Caches
 
 
diff --git a/asynq/tests/test_channels.py b/asynq/tests/test_channels.py
index 7512a88..303f33a 100644
--- a/asynq/tests/test_channels.py
+++ b/asynq/tests/test_channels.py
@@ -16,7 +16,6 @@
 from asynq import asynq, async_proxy, ConstFuture
 from collections import deque
 
-
 # TODO(alex): finish w/this test
 
 
diff --git a/asynq/tests/test_contexts.py b/asynq/tests/test_contexts.py
index ad4a43f..f3bb0a6 100644
--- a/asynq/tests/test_contexts.py
+++ b/asynq/tests/test_contexts.py
@@ -19,7 +19,6 @@
 from .debug_cache import mc
 from .caching import ExternalCacheBatchItem
 
-
 current_context = None
 change_amount = 0
 
diff --git a/asynq/tests/test_multiple_inheritance.py b/asynq/tests/test_multiple_inheritance.py
index 3f46149..d2930bc 100644
--- a/asynq/tests/test_multiple_inheritance.py
+++ b/asynq/tests/test_multiple_inheritance.py
@@ -22,7 +22,6 @@
 
 from asynq import asynq
 
-
 called = {}
 
 
diff --git a/asynq/utils.py b/asynq/utils.py
index 8ec36fa..3f94da2 100644
--- a/asynq/utils.py
+++ b/asynq/utils.py
@@ -16,7 +16,6 @@
 from . import async_task
 from . import _debug
 
-
 _debug_options = _debug.options